Problems in Physical Chemistry for JEE

Narendra Avasthi

Chapter 4

Thermodynamics - all with Video Answers

Educators

Chapter Questions

Problem 1

Out of molar entropy (I), specific volume (II), heat capacity (III), volume (IV), extensive properties are :
(a) I, II
(b) I, II, IV
(c) II, III
(d) III, IV

Ajay Singhal

Ajay Singhal

Numerade Educator

Problem 2

Out of internal energy (I), boiling point (II), pH (III) and E.M.F of the cell (IV) intensive properties are :
(a) I, II
(b) II, III, $\mathrm{N}$
(c) I, III, IV
(d) All of these

Ajay Singhal

Numerade Educator

Problem 2

Which of the following value of $\Delta H_{f}^{\circ}$ represent that the product is least stable?
(a) $-94.0 \mathrm{kcal} \mathrm{mol}^{-1}$
(b) $-231.6 \mathrm{kcal} \mathrm{mol}^{-1}$
(c) $+21.4 \mathrm{kcal} \mathrm{mol}^{-1}$
(d) $+64.8 \mathrm{kcal} \mathrm{mol}^{-1}$

Ajay Singhal

Numerade Educator

Problem 3

Thermodynamic equilibrium involves
(a) Chemical equilibrium
(b) Mechanical equilibrium
(c) Thermal equilibrium
(d) All the above simultaneously

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Numerade Educator

Problem 4

Which has maximum internal energy at $290 \mathrm{~K}$ ?
(a) Neon gas
(b) Nitrogen gas
(c) Ozone gas
(d) Equal

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Numerade Educator

Problem 5

A $10 \mathrm{~g}$ piece of iron $\left(C=0.45 \mathrm{~J} / 8^{\circ} \mathrm{C}\right)$ at $100^{\circ} \mathrm{C}$ is dropped into $25 \mathrm{~g}$ of water $\left(C=4.2 \mathrm{~J} / \mathrm{g}^{\circ} \mathrm{C}\right)$ at
$27^{\circ} \mathrm{C}$. Find temperature of the iron and water system at thermal equilibrium.
(a) $30^{\circ} \mathrm{C}$
(b) $33^{\circ} \mathrm{C}$
(c) $40^{\circ} \mathrm{C}$
(d) None of these

Ajay Singhal

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Problem 6

When freezing of a liquid takes place in a system :
(a) may have $q>0$ or $q<0$ depending on the liquid
(b) is represented by $q>0$
(c) is represented by $q<0$
(d) has $q=0$

Ajay Singhal

Numerade Educator

Problem 7

Mechanical work is specially important in systems that contain.
(a) gas-liquid
(b) liquid-liquid
(c) solid-solid
(d) amalgam

Ajay Singhal

Numerade Educator

Problem 8

Mechanical work is specially important in systems that contain.
(a) gas-liquid
(b) liquid-liquid
(c) solid-solid
(d) amalgam

Ajay Singhal

Numerade Educator

Problem 9

Determine which of the following reactions taking place at constant pressure represent surrounding that do work on the system environment
I. $4 \mathrm{NH}_{3}(g)+7 \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{NO}_{2}(g)+6 \mathrm{H}_{2} \mathrm{O}(g)$
II. $\mathrm{CO}(g)+2 \mathrm{H}_{2}(g) \longrightarrow \mathrm{CH}_{3} \mathrm{OH}(l)$
III. $\mathrm{C}(s$, graphite $)+\mathrm{H}_{2} \mathrm{O}(g) \longrightarrow \mathrm{CO}(g)+\mathrm{H}_{2}(g)$
IV. $\mathrm{H}_{2} \mathrm{O}(s) \longrightarrow \mathrm{H}_{2} \mathrm{O}(l)$
(a) III, IV
(b) II and III
(c). II, IV
(d) I and II, IV

Ajay Singhal

Numerade Educator

Problem 10

A sample of liquid in a thermally insulated container (a calorimeter) is stirred for $2 \mathrm{hr}$. by a mechanical linkage to a motor in the surrounding, for this process :
(a) $w<0 ; q=0 ; \Delta U=0$
(b) $w>0 ; q>0 ; \Delta U>0$
(c) $w<0 ; q>0 ; \Delta U=0$
(d) $w>0 ; q=0 ; \Delta U>0$

Ajay Singhal

Numerade Educator

Problem 11

A system undergoes a process in which $\Delta E=+300 \mathrm{~J}$ while absorbing $400 \mathrm{~J}$ of heat energy and undergoing an expansion against $0.5$ bar. What is the change in the volume (in $\mathrm{L}$ )?
(a) 4
(b) 5
(c) 2
(d) 3

Ajay Singhal

Numerade Educator

Problem 12

An ideal gas expands against a constant external pressure of $2.0$ atmosphere from 20 litre 40 litre and absorbs $10 \mathrm{~kJ}$ of heat from surrounding. What is the change in internal energy the system? $\quad$ (Given : 1 atm-litre $=101.3 \mathrm{~J}$ )
(a) $4052 \mathrm{~J}$
(b) $5948 \mathrm{~J}$
(c) $14052 \mathrm{~J}$
(d) $9940 \mathrm{~J}$

Ajay Singhal

Numerade Educator

Problem 13

One mole of an ideal gas at $25^{\circ} \mathrm{C}$ expands in volume from $1.0 \mathrm{~L}$ to $4.0 \mathrm{~L}$ at constant . temperature. What work (in $J$ ) is done if the gas expands against vacuum $\left(P_{\text {cxtemal }}=0\right)$ ?
(a) $-4.0 \times 10^{2}$
(b) $-3.0 \times 10^{2}$
(c) $-1.0 \times 10^{2}$
(d) Zero

Ajay Singhal

Numerade Educator

Problem 14

At $25^{\circ} \mathrm{C}$, a $0.01$ mole sample of a gas is compressed from $4.0 \mathrm{~L}$ to $1.0 \mathrm{~L}$ at constant temperature. What is the work done for this process if the external pressure is $4.0$ bar?
(a) $1.6 \times 10^{3} \mathrm{~J}$
(b) $8.0 \times 10^{2} \mathrm{~J}$
(c) $4.0 \times 10^{2} \mathrm{~J}$
(d) $1.2 \times 10^{3} \mathrm{~J}$

Ajay Singhal

Numerade Educator

Problem 15

Calculate the work done (in $J$ ) when $4.5 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O}_{2}$ reacts against a pressure of $1.0 \mathrm{~atm}$ at $25^{\circ} \mathrm{C}$
$$
2 \mathrm{H}_{2} \mathrm{O}_{2}(l) \longrightarrow \mathrm{O}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(l)
$$
(a) $-1.63 \times 10^{2}$
(b) $4.5 \times 10^{2}$
(c) $3.2 \times 10^{2}$
(d) $-6.1 \times 10^{2}$

Ajay Singhal

Numerade Educator

Problem 16

2 mole of zinc is dissolved in $\mathrm{HCl}$ at $25^{\circ} \mathrm{C}$. The work done in open vessel is :
(a) $-2.477 \mathrm{~kJ}$
(b) $-4.955 \mathrm{~kJ}$
(c) $0.0489 \mathrm{~kJ}$
(d) None

Ajay Singhal

Numerade Educator

Problem 17

Temperature of 1 mole of a gas is increased by $2^{\circ} \mathrm{C}$ at constant pressure, work done is :
(a) $R$
(b) $2 R$
(c) $R / 2$
(d) $3 R$

Ajay Singhal

Numerade Educator

Problem 18

A sample of an ideal gas is expanded $1 \mathrm{~m}^{3}$ to $3 \mathrm{~m}^{3}$ in a reversible process for which $P=K V^{2}$, with $K=6 \mathrm{bar} / \mathrm{m}^{6}$. Work done by the gas is :
(a) $5200 \mathrm{~kJ}$
(b) $15600 \mathrm{~kJ}$
(c) $52 \mathrm{~kJ}$
(d) $5267.6 \mathrm{~kJ}$

Ajay Singhal

Numerade Educator

Problem 19

A given mass of gas expands reversibly from the state $A$ to the state $B$ by three paths 1,2 and 3 as shown in the figure. If $w_{1}, w_{2}$ and $w_{3}$ respectively be the work done by the gas along three paths then:
(a) $w_{1}>w_{2}>w_{3}$
(b) $w_{1}<w_{2}<w_{3}$
(c) $w_{1}=w_{2}=w_{3}$
(d) $w_{2}<w_{3}<w_{1}$

Ajay Singhal

Numerade Educator

Problem 20

Heat absorbed by a system in going through a cyclic process shown in figure is :
(a) $10^{7} \pi \mathrm{J}$
(b) $10^{6} \pi \mathrm{J}$
(c) $10^{2} \pi \mathrm{J}$
(d) $10^{4} \pi \mathrm{J}$

Ajay Singhal

Numerade Educator

Problem 21

In the cyclic process shown in $P-V$ diagram, the magnitude of the work done is :
(a) $\pi\left(\frac{P_{2}-P_{1}}{2}\right)^{2}$
(b) $\pi\left(\frac{V_{2}-V_{1}}{2}\right)^{2}$
(c) $\frac{\pi}{4}\left(P_{2}-P_{1}\right)\left(V_{2}-V_{1}\right)$
(d) $\pi\left(V_{2}-V_{1}\right)^{2}$

Ajay Singhal

Numerade Educator

Problem 22

An ideal gas is taken around the cycle $A B C A$ as shown in $P-V$ diagram. The net work done during the cycle is equal to :
(a) $12 P_{1} V_{1}$
(b) $6 P_{1} V_{1}$
(c) $5 P_{1} V_{1}$
(d) $P_{1} V_{1}$

Ajay Singhal

Numerade Educator

Problem 23

An ideal gas is at pressure $P$ and temperature $T$ in a box, which is kept in vacuum with in a large container. The wall of the box is punctured. What happens as the gas occupies entire container?
(a) It's temperature falls
(b) Its temperature rises
(c) Its temperature remains the same
(d) Unpredictable

Ajay Singhal

Numerade Educator

Problem 24

In diagrams (1 to 4), variation of volume with changing pressure is shown. A gas is taken along the path $A B C D$. The change in internal energy of the gas will be :
(a) Positive in all the cases (1) to (4)
(b) Positive in cases $(1),(2),(3)$ but zero in case $(4)$
(c) Negative in cases $(1),(2),(3)$ but zero in case $(4)$
(d) Zero in all the cases

Ajay Singhal

Numerade Educator

Problem 25

If the door of a refrigerator is kept open, the room in which the refrigerator is kept
(a) gets cooled $\cdots:$
(b) gets heated
(c) neither gets cooled nor gets heated:
$\cdots v$
(d) gets cooled or heated depending on the initial temperature of the room

Ajay Singhal

Numerade Educator

Problem 26

The temperature of an ideal gas increases in an :
(b) isothermal expansion
(a) adiabatic expanston
(c) adiabatic compression

Ajay Singhal

Numerade Educator

Problem 27

For two mole of an ideal gas :
(a) $C_{v}-C_{p}=R$
(b) $C_{p}^{\prime \prime \prime} \perp C_{v} \doteq 2 R$
(c) $\vec{C}_{p}^{\prime}-C_{v}=R$
(d) $C_{v}-C_{p}=2 R$

Ajay Singhal

Numerade Educator

Problem 28

Which of the following exprésstons' is 'true for an ideal gas ?
(a) $\left(\frac{\partial V}{\partial T}\right)_{P}=0$
(b) $\left(\frac{\partial P}{\partial T}\right)_{V: n}=0^{6}$
(c) $\left(\frac{\partial U}{\partial V}\right)_{T}=0$
(d) $\left(\frac{\partial U}{\partial T}\right)_{V}=0$

Ajay Singhal

Numerade Educator

Problem 29

Liquefied oxygen at 1 atmosphere is heated from $50 \mathrm{~K}$ to $300 \mathrm{~K}$ by supplying heat at a constant rate. The graph that correctly shows the relationship between temperature and time is :

Ajay Singhal

Numerade Educator

Problem 30

If $w_{1}, w_{2}, w_{3}$ and $w_{4}$ for an ideal gas are magnitude of work done in isothermal, adiabatic, isobaric and isochoric reversible expansion processes, the correct order will be :
(a) $w_{1}>w_{2}>w_{3}>w_{4}$
$\therefore:$
$\therefore \cdots, \$ (b) $w_{3}>w_{2}>w_{1}>w_{4}$
(c) $w_{3}>w_{2}>w_{4}>w_{1}$
8
(d) $w_{3}$ > $w_{1}>w_{2}>w_{4}$

Ajay Singhal

Numerade Educator

Problem 31

For a closed container containing 100 mole of an ideal gas fitted with movable, frictionless, weightless piston operating such that pressure of gas remains constant at $8.21$ atm, which graph represents correct variation of $\log V$ vs. log $T$ where $V$ is in litre and $T$ in kelvin.

Ajay Singhal

Numerade Educator

Problem 32

A gas expands against a variable pressure given by $P=\frac{40}{V}$ (where $P$ in atm and $V$ in $\mathrm{L}$ ). During expansion from volume of i litre to 10 litre, the gas undergoes a change in internal energy of $400 \mathrm{~J}$. How much heat is absorbed by the gas'during expansion?
(a) $46 \mathrm{~J}$
(b) $4660 \mathrm{~J}^{2} \ldots$ - (c) $5065.8 \mathrm{~J}$
(d) $4260 \mathrm{~J}$

Ajay Singhal

Numerade Educator

Problem 33

2 mole of an ideal gas at $27^{\circ} \mathrm{C}$ expands' isathermally and reversibly from a volume of 4 litre to 40 litre. The work dorie (in $k$ ) by the gas is : ${ }^{1} \therefore$.
(a) $w=-28.72 \mathrm{~kJ}$
(c) $w=-5.736 \mathrm{~kJ}$
$0^{2}$

Ajay Singhal

Numerade Educator

Problem 34

10 mole of ideal gas expand isothermally and reversibly from a pressure of $10 \mathrm{~atm}$ to $1 \mathrm{~atm}$ at $300 \mathrm{~K}$. What is the largest mass which can lifted through a height of 100 meter?
(a) $31842 \mathrm{~kg}$
(b) $58.55 \mathrm{~kg}$
(c) $342.58 \mathrm{~kg}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 35

A heat engine carries one mole of an ideal mono-atomic gas around the cycle as shown in the figure. Select the correct option:
(a) $q_{A B}=450 R$ and $q_{C A}=-450 R$
(b) $q_{A B}=450 R$ and $q_{C A}=-225 R$
(c) $q_{A B}=450 R$ and $q_{C A}=-375 R$
(d) $q_{A B}=375 R$ and $q_{C A}=-450 R$

Ajay Singhal

Numerade Educator

Problem 36

What is the final temperature of $0.10$ mole monoatomic ideal gas that performs 75 cal of work adiabatically if the initial temperature is $227^{\circ} \mathrm{C}$ ? (use $R=2 \mathrm{cal} / \mathrm{K}$ -mol $)$
(a) $250 \mathrm{~K}$
(b) $300 \mathrm{~K}$
(c) $350 \mathrm{~K}$
(d) $750 \mathrm{~K}$

Ajay Singhal

Numerade Educator

Problem 37

The work done by the gas in reversible adiabatic expansion process is :
(a) $\frac{P_{2} V_{2}-P_{1} V_{1}}{\gamma-1}$
(b) $\frac{n R\left(T_{1}-T_{2}\right)}{\gamma-1}$
(c) $\frac{P_{2} V_{2}-P_{1} V_{1}}{\gamma}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 38

During an adiabatic process, the pressure of gas is found to be proportional to the cube of its absolute temperature. The ratio of $\left(C_{p, m} / C_{v, m}\right)$ for gas is :
(a) $\frac{3}{2}$
(b) $\frac{5}{3}$
(c) $\frac{7}{2}$
(d) $\frac{4}{3}$

Ajay Singhal

Numerade Educator

Problem 38

During an adiabatic process, the pressure of gas is found to be proportional to the cube of its absolute temperature. The ratio of $\left(C_{p, m} / C_{v, m}\right)$ for gas is :
(a) $\frac{3}{2}$
(b) $\frac{5}{3}$
(c) $\frac{7}{2}$
(d) $\frac{4}{3}$

Ajay Singhal

Numerade Educator

Problem 39

A gas expands adiabatically at constant pressure such that $T \propto V^{-1 / 2}$ The value of $\gamma\left(C_{p, m} / C_{w m}\right)$ of the gas will be :
(a) $1.30$
(b) $1.50$
(c) $1.70$
(d) 2

Ajay Singhal

Numerade Educator

Problem 40

For a reversible adiabatic ideal gas expansion $\frac{\mathrm{a} P}{P}$ is equal to :
(a) $\gamma \frac{d V}{V}$
(b) $-\gamma \frac{d V}{V}$
(c) $\left(\frac{\gamma}{\gamma-1}\right) \frac{d V}{V}$
(d) $\frac{d V}{V}$

Ajay Singhal

Numerade Educator

Problem 41

$P-V$ plot for two gases (assuming ideal)during adiabatic processes are given in the Fig. Plot $A$ and plot $B$ should correspond respectively to:
(a) $\mathrm{He}$ and $\mathrm{H}_{2}$
(b) $\mathrm{H}_{2}$ and $\mathrm{He}$
(c) He and Ne
(d) $\mathrm{H}_{2}$ and $\mathrm{Cl}_{2}$

Ajay Singhal

Numerade Educator

Problem 42

Calculate the final temperature of a monoatomic ideal gas that is compressed reversible and adiabatically from $16 \mathrm{~L}$ to $2 \mathrm{~L}$ at $300 \mathrm{~K}$ :
(a) $600 \mathrm{~K}$
(b) $1044.6 \mathrm{~K}$
(c) $1200 \mathrm{~K}$
(d) $2400 \mathrm{~K}$

Ajay Singhal

Numerade Educator

Problem 43

5 mole of an ideal gas expand isothermally and irreversibly from a pressure of 10 atm to 1 atm against a constant external pressure of 1 atm. $w_{\mathrm{irr}}$ at $300 \mathrm{~K}$ is :
(a) $-15.921 \mathrm{~kJ}$
(b) $-11.224 \mathrm{~kJ}$
(c) $-110.83 \mathrm{~kJ}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 44

With what minimum pressure (in $k P a$ ), a given volume of an ideal gas $\left(C_{p, m}=7 / 2 R\right.$ ), originally at $400 \mathrm{~K}$ and $100 \mathrm{kPa}$ pressure can be compressed irreversibly adiabatically in order to raise its temperature to $600 \mathrm{~K}$ :
(a) $362.5 \mathrm{kPa}$
(b) $275 \mathrm{kPa}$
(c) $437.5 \mathrm{kPa}$
(d) $550 \mathrm{kPa}$

Ajay Singhal

Numerade Educator

Problem 45

The work done in adiabatic compression of 2 mole of an ideal monoatomic gas against constant external pressure of $2 \mathrm{~atm}$ starting from initial pressure of $1 \mathrm{~atm}$ and initial temperature of $300 \mathrm{~K}$ ( $R=2 \mathrm{cal} / \mathrm{mol}$ -degree $)$
(a) $360 \mathrm{cal}$
(b) $720 \mathrm{cal}$
(c) $800 \mathrm{cal}$
(d) $1000 \mathrm{cal}$

Supratim Pal

Numerade Educator

Problem 46

One mole of an ideal gas $\left(C_{v, m}=\frac{5}{2} R\right)$ at $300 \mathrm{~K}$ and $5 \mathrm{~atm}$ is expanded adiabatically to a final pressure of 2 atm against a constant pressure of 2 atm. Final temperature of the gas is :
(a) $270 \mathrm{~K}$
(b) $273 \mathrm{~K}$
(c) $248.5 \mathrm{~K}$
(d) $200 \mathrm{~K}$

Ajay Singhal

Numerade Educator

Problem 47

10 litre of a non linear polyatomic ideal gas at $127^{\circ} \mathrm{C}$ and 2 atm pressure is suddenly released to 1 atm pressure and the gas expanded adiabatically against constant external pressure, the final temperature and volume of the gas respectively are.
(a) $T=350 \mathrm{~K} ; V=17.5 \mathrm{~L}$
(b) $T=300 \mathrm{~K} ; V=15 \mathrm{~L}$
(c) $T=250 \mathrm{~K} ; V=12.5 \mathrm{~L}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 48

Calculate average molar heat capacity at constant volume of gaseous mixture contained 2 mole of each of two ideal gases $A\left(C_{\mathrm{v}, m}=\frac{3}{2} R\right)$ and $B\left(C_{\mathrm{v}, m}=\frac{5}{2} R\right):$
(a) $R$
(b) $2 R$
(c) $3 R$
(d) $8 R$

Ajay Singhal

Numerade Educator

Problem 49

$0.5$ mole each of two ideal gases $A\left(C_{v, m}=\frac{5}{2} R\right)$ and $B\left(C_{v, m}=3 R\right)$ are taken in a container and expanded reversibly and adiabatically, during this process.temperature of gaseous mixture decreased from $350 \mathrm{~K}$ to $250 \mathrm{~K}$. Find $\Delta H$ (in cal/mol) for the process :
(a) $-100 R$
(b) $-137.5 R$
(c) $-375 R$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 50

A cyclic process $A B C D$ is shown in $P-V$ diagram for an ideal gas. Which of the following diagram represents the same process?

Ajay Singhal

Numerade Educator

Problem 51

$36 \mathrm{~mL}$ of pure water takes 100 sec to evaporate from a vessel and heater connected to an electric source which delivers 806 watt. The $\Delta H_{\text {vaporization }}$ of $\mathrm{H}_{2} \mathrm{O}$ is :
(a) $40.3 \mathrm{~kJ} / \mathrm{mol}$
(b) $43.2 \mathrm{~kJ} / \mathrm{mol}$
(c) $4.03 \mathrm{~kJ} / \mathrm{mol}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 52

For the reaction $: \mathrm{PCl}_{5}(g) \longrightarrow \mathrm{PCl}_{3}(g)+\mathrm{Cl}_{2}(g) \vdots$
(a) $\Delta H=\Delta E$
(b) $\Delta H>\Delta E$
(c) $\Delta H<\Delta E$
(d) None of the above

Ajay Singhal

Numerade Educator

Problem 53

Consider the reaction at $300 \mathrm{~K}$
$$
\mathrm{H}_{2}(g)+\mathrm{Cl}_{2}(g) \longrightarrow 2 \mathrm{HCl}(g) ; \quad \Delta H^{\circ}=-185 \mathrm{~kJ}
$$
If 2 mole of $\mathrm{H}_{2}$ completely react with 2 mole of $\mathrm{Cl}_{2}$ to form $\mathrm{HCl}$. What is $\Delta U^{\circ}$ for this reaction?
(a) 0
(b) $-185 \mathrm{~kJ}$
(c) $370 \mathrm{~kJ}$
(d) None of thace

Ajay Singhal

Numerade Educator

Problem 54

Which of the indicated relationship is correct for the following exothermic reaction carried out at constant pressure?
$$
\mathrm{CO}(g)+3 \mathrm{H}_{2}(g) \longrightarrow \mathrm{CH}_{4}(g)+\mathrm{H}_{2} \mathrm{O}(g)
$$
(a) $\Delta E=\Delta H$
(b) $\Delta E>\Delta H$
(c) $w<0$
(d) $q>0$

Ajay Singhal

Numerade Educator

Problem 55

One mole of an ideal gas undergoes a change of state $(2.0 \mathrm{~atm}, 3.0 \mathrm{~L})$ to $(2.0 \mathrm{~atm}, 7.0 \mathrm{~L})$ with a change in internal energy $(\Delta U)=30 \mathrm{~L}-\mathrm{atm} .$ The change in enthalpy $(\Delta H)$ of the process in L-atm :
(a) 22
(b) 38
(c) 25
(d) None of thése

Ajay Singhal

Numerade Educator

Problem 56

What is the change in internal energy when a gas contracts from $377 \mathrm{~mL}$ to $177 \mathrm{~mL}$ under a constant pressure of 1520 torr, while at the same time being cooled by removing 124 J heat?
(a) $40.52 \mathrm{~J}$
(b) $-83.48 \mathrm{~J}$
(c) $-248 \mathrm{~J}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 57

For the real gases reaction $2 \mathrm{CO}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{CO}_{2}(g) ; \Delta H=-560 \mathrm{~kJ} .$ In 10 litre rigid
vessel at $500 \mathrm{~K}$ the initial pressure is 70 bar and after the reaction it becomes 40 bar. The change in internal energy is :
(a) $-557 \mathrm{~kJ}$
(b) $-530 \mathrm{~kJ}$
(c) $-563 \mathrm{~kJ}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 58

One mole of a non-ideal gas undergoes a change of state from $(1.0 \mathrm{~atm}, 3.0 \mathrm{~L}, 200 \mathrm{~K})$ to $(4.0$ atm, $5.0 \mathrm{~L}, 250 \mathrm{~K}$ ) with a change in internal energy $(\Delta U)=40 \mathrm{~L}$ -atm. The change in enthalpy of the process in L-atm :
(a) 43
(b) 57
(c) 42
(d) None of these

Ajay Singhal

Numerade Educator

Problem 59

Consider the reaction at $300 \mathrm{~K}$
$$
\mathrm{C}_{6} \mathrm{H}_{6}(l)+\frac{15}{2} \mathrm{O}_{2}(g) \longrightarrow 6 \mathrm{CO}_{2}(g)+3 \mathrm{H}_{2} \mathrm{O}(l) ; \Delta H=-3271 \mathrm{~kJ}
$$
What is $\Delta U$ for the combustion of $1.5$ mole of benzene at $27^{\circ} \mathrm{C}$ ?
(a) $-3267.25 \mathrm{~kJ}$
(b) $-4900.88 \mathrm{~kJ}$
(c) $-4906.5 \mathrm{~kJ}$
(d) $-3274.75 \mathrm{~kJ}$

Ajay Singhal

Numerade Educator

Problem 60

For the reaction; $\mathrm{FeCO}_{3}(s) \longrightarrow \mathrm{FeO}(s)+\mathrm{CO}_{2}(g) ; \Delta H=82.8 \mathrm{~kJ}$ at $25^{\circ} \mathrm{C}$, what is $(\Delta E$ or $\Delta U)$
at $25^{\circ} \mathrm{C}$ ?
(a) $82.8 \mathrm{~kJ}$
(b) $80.32 \mathrm{~kJ}$
(c) $-2394.77 \mathrm{~kJ}$
(d) $85.28 \mathrm{~kJ}$

Ajay Singhal

Numerade Educator

Problem 61

At $5 \times 10^{5}$ bar pressure density of diamond and graphite are $3 \mathrm{~g} / \mathrm{cc}$ and $2 \mathrm{~g} / \mathrm{cc}$ respectively, at certain temperature ' $T$ '. Find the value of $\Delta U-\Delta H$ for the conversion of 1 mole of graphite to 1 mole of diamond at temperature ' $T^{\prime}$ :
(a) $100 \mathrm{~kJ} / \mathrm{mol}$
(b) $50 \mathrm{~kJ} / \mathrm{mol}$
(c) $-100 \mathrm{~kJ} / \mathrm{mol}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 62

Predict which of the following reaction(s) has a positive entropy change?
I. $\mathrm{Ag}^{+}(a q)+\mathrm{Cl}^{-}(a q) \longrightarrow \mathrm{AgCl}(s)$
II. $\mathrm{NH}_{4} \mathrm{Cl}(s) \longrightarrow \mathrm{NH}_{3}(g)+\mathrm{HCl}(g)$

Ajay Singhal

Numerade Educator

Problem 63

Predict which of the following reaction(s) has a negative entropy change?
I. $\mathrm{CH}_{4}(g)+2 \mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(l)$
II. $\mathrm{NH}_{3}(g)+\mathrm{HCl}(g) \longrightarrow \mathrm{NH}_{4} \mathrm{Cl}(s)$
III. $2 \mathrm{KClO}_{4}(s) \longrightarrow 2 \mathrm{KClO}_{3}(s)+\mathrm{O}_{2}(g)$
(a) III
(b) II
(c) I and II
(d) I

Ajay Singhal

Numerade Educator

Problem 64

Which of the following reactions is associated with the most negative change in entropy?
(a) $2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{SO}_{3}(g)$
(b) $\mathrm{C}_{2} \mathrm{H}_{4}(g)+\mathrm{H}_{2}(g) \longrightarrow \mathrm{C}_{2} \mathrm{H}_{6}(g)$
(c) $\mathrm{C}(s$, graphite $)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)$
(d) $\left.3 \mathrm{C}_{n} \mathrm{H}_{0} \mathrm{~g}\right) \longrightarrow \mathrm{C}_{\mathrm{H}} \mathrm{H}_{\mathrm{C}}(\mathrm{l})$

Ajay Singhal

Numerade Educator

Problem 65

When two mole of an ideal gas $\left(C_{p, m}=\frac{5}{2} R\right)$ heated from $300 \mathrm{~K}$ to $600 \mathrm{~K}$ at constant pressure.
The change in entropy of gas $(\Delta S)$ is :
$\begin{array}{llll}\text { (b) }-\frac{3}{2} R \ln 2 & \text { (c) } 5 R \ln 2 & \text { (d) } \frac{5}{2} R \ln 2\end{array}$
(a) $\frac{3}{2} R \ln 2$

Ajay Singhal

Numerade Educator

Problem 66

Which of the following expression for an irreversible process:
(a) $d S>\frac{d q}{T}$
(b) $d S=\frac{d q}{T}$
(c) $d S<\frac{d q}{T}$
(d) $d S=\frac{d U}{T}$

Ajay Singhal

Numerade Educator

Problem 67

Which of the following expressions is known as Clausius inequality?
(a) $\oint \frac{d q}{T} \leq 0$
(b) $\oint \frac{d s}{T}=0$
(c) $\oint \frac{T}{d q} \leq 0$
(d) $\oint \frac{d q}{T} \geq 0$

Ajay Singhal

Numerade Educator

Problem 68

In problem 65, calculate $\Delta S_{\mathrm{gas}}$ if process is carried out at constant volume :
(a) $5 R \ln 2$
(b) $\frac{3}{2} R \ln 2$
(c) $3 R \ln 2$
(d) $-3 R \ln 2$

Ajay Singhal

Numerade Educator

Problem 69

If one mole of an ideal gas $\left(C_{p, m}=\frac{5}{2} R\right)$ is expanded isothermally at 300 until it's volume is tripled, then change in entropy of gas is :
(a) zero
(b) infinity
(c) $\frac{5}{2} R \ln 3$
(d) $R \ln 3$

Ajay Singhal

Numerade Educator

Problem 70

In previous problem if expansion is carried out freely $\left(P_{\operatorname{ext}}=0\right)$, then $\Delta S$ is :
(a) zero
(b) infinity
(c) $R \ln 3$
(d) None

Ajay Singhal

Numerade Educator

Problem 71

When one mole of an ideal gas is compressed to half of its initial volume and simultaneously heated to twice its initial temperature, the change in entropy of gas $(\Delta S)$ is :
(a) $C_{p, m} \ln 2$
(b) $C_{v, m} \ln 2$
(c) $R \ln 2$
(d) $\left(C_{v, m}-R\right) \ln 2$

Ajay Singhal

Numerade Educator

Problem 72

What is the change in entropy when $2.5$ mole of water is heated from $27^{\circ} \mathrm{C}$ to $87^{\circ} \mathrm{C} ?$ Assume that the heat capacity is constant. $\left(C_{p, m}\left(\mathrm{H}_{2} \mathrm{O}\right)=4.2 \mathrm{~J} / \mathrm{g}-\mathrm{K} \ln (1.2)=0.18\right)$
(a) $16.6 \mathrm{~J} / \mathrm{K}$
(b) $9 \mathrm{~J} / \mathrm{K}$
(c) $34.02 \mathrm{~J} / \mathrm{K}$
(d) $1.89 \mathrm{~J} / \mathrm{K}$

Ajay Singhal

Numerade Educator

Problem 73

Calculate standard entropy change in the reaction
$$
\mathrm{Fe}_{2} \mathrm{O}_{3}(s)+3 \mathrm{H}_{2}(g) \longrightarrow 2 \mathrm{Fe}(s)+3 \mathrm{H}_{2} \mathrm{O}(l)
$$
Given : $S_{m}^{\circ}\left(\mathrm{Fe}_{2} \mathrm{O}_{3}, \mathrm{~S}\right)=87.4, S_{m}^{\circ}(\mathrm{Fe}, S)=27.3$
$S_{m}^{\circ}\left(\mathrm{H}_{2}, g\right)=130.7, S_{m}^{\circ}\left(\mathrm{H}_{2} \mathrm{O}, l\right)=69.9 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$

Ajay Singhal

Numerade Educator

Problem 74

Calculate the entropy change $(\mathrm{J} / \mathrm{mol} \mathrm{K})$ of the given reaction. The molar entropies [J/K-mol] are given in brackets after each substance. $2 \mathrm{PbS}(s)[91.2]+3 \mathrm{O}_{2}(g)[205.1] \longrightarrow 2 \mathrm{PbO}(s)[66.5]+2 \mathrm{SO}_{2}(g)[248.2]$
(a) $-113.5$
(b) $-168.3$
(c) $+72.5$
(d) $-149.2$

Ajay Singhal

Numerade Educator

Problem 75

Given $\Delta_{r} S^{\circ}=-266$ and the listed $\left[S_{m}^{\circ}\right.$ values] calculate $S^{\circ}$ for $\mathrm{Fe}_{3} \mathrm{O}_{4}(s)$ :
$4 \mathrm{Fe}_{3} \mathrm{O}_{4}(s)[\ldots . .]+\mathrm{O}_{2}(g)[205] \longrightarrow 6 \mathrm{Fe}_{2} \mathrm{O}_{3}(s)[87]$
(a) $+111.1$
(b) $+122.4$
(c) $145.75$
(d) $248.25$

Ajay Singhal

Numerade Educator

Problem 76

The entropy change for a phase transformation is :
(a) $\frac{\Delta U}{\gamma+d T}$
(b) $\frac{\Delta T}{\Delta H}$
(c) $\frac{\Delta H}{T}$
(d) $\frac{\Delta H+\Delta G}{T}$

Ajay Singhal

Numerade Educator

Problem 77

What is the melting point of benzene if $\Delta H_{\text {fusion }}=9.95 \mathrm{~kJ} / \mathrm{mol}$ and $\Delta S_{\text {fusion }}=35.7 \mathrm{~J} / \mathrm{K}$ -mol?
(a) $278.7^{\circ} \mathrm{C}$
(b) $278.7 \mathrm{~K}$
(c) $300 \mathrm{~K}$
(d) $298 \mathrm{~K}$

Ajay Singhal

Numerade Educator

Problem 78

$\Delta S$ for freezing of $10 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O}(l)$ (enthalpy of fusion is $80 \mathrm{cal} / \mathrm{g}$ ) at $0^{\circ} \mathrm{C}$ and 1 atm is :
(a) $12.25 \mathrm{~J} / \mathrm{K}$
(b) $-0.244 \mathrm{~J} / \mathrm{K}$
(c) $-2.93 \mathrm{~J} / \mathrm{K}$
(d) $-12.25 \mathrm{~J} / \mathrm{K}$

Ajay Singhal

Numerade Educator

Problem 79

Chloroform has $\Delta H_{\text {vaporization }}=29.2 \mathrm{~kJ} / \mathrm{mol}$ and boils at $61.2^{\circ} \mathrm{C} .$ What is the value of $\Delta S_{\text {vaporization }}$ for chloroform?
(a) $87.3 \mathrm{~J} / \mathrm{mol}-\mathrm{K}$
(b) $477.1 \mathrm{~J} / \mathrm{mol}-\mathrm{K}$
(c) $-87.3 \mathrm{~J} / \mathrm{mol}-\mathrm{K}$
(d) $-477.1 \mathrm{~J} / \mathrm{mol}-\mathrm{K}$

Ajay Singhal

Numerade Educator

Problem 80

The entropy of vaporization of benzene is $85 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$. When $117 \mathrm{~g}$ benzene vaporizes at it's normal boiling point, the entropy change of surrounding is :
(a) $-85 \mathrm{JK}^{-1}$
(b) $-85 \times 1.5 \mathrm{JK}^{-1}$
(c) $85 \times 1.5 \mathrm{JK}^{-1}$
(d) None of these Identify the correct statement regarding entropy

Ajay Singhal

Numerade Educator

Problem 81

Identify the correct statement regarding entropy
(a) At absolute zero temperature, the entropy of perfectly crystalline substances is $+\mathrm{ve}$
(b) At absolute zero temperature entropy of perfectly crystalline substance is taken to be zero
(c) At $0^{\circ} \mathrm{C}$ the entropy of a perfectly crystalline substance is taken to be zero
(d) At absolute zero temperature, the entropy of all crystalline substances is taken to be zero

Ajay Singhal

Numerade Educator

Problem 82

Calculate $\Delta S$ for following process:
$$
\underset{\text { at } 100 \mathrm{~K}}{X(s)} \longrightarrow \underset{\text { at } 200 \mathrm{~K}}{X(l)}
$$
Given : Melting point of $X_{(s)}=100 \mathrm{~K} ; \Delta H_{\text {Fusion }}=20 \mathrm{~kJ} / \mathrm{mol} ; C_{p, m}(X, l)=10 \mathrm{~J} / \mathrm{mol} \mathrm{K}$
(a) $26.93 \mathrm{~J} / \mathrm{K}$
(b) $206.93 \mathrm{~J} / \mathrm{K}$
(c) $203 \mathrm{~J} / \mathrm{K}$
(d) $206.93 \mathrm{~kJ} / \mathrm{K}$

Ajay Singhal

Numerade Educator

Problem 83

For a perfectly crystalline solid $C_{p, m}=a T^{3}$, where $a$ is constant. If $C_{p, m}$ is $0.42 \mathrm{~J} / \mathrm{K}$ mol at $10 \mathrm{~K}$, molar entropy at $20 \mathrm{~K}$ is :
(a) $0.42 \mathrm{~J} / \mathrm{K}$ mol
(b) $0.14 \mathrm{~J} / \mathrm{K} \mathrm{mol}$
(c) $1.12 \mathrm{~J} / \mathrm{K} \mathrm{mol}$
(d) zero

Ajay Singhal

Numerade Educator

Problem 84

Consider the following spontaneous reaction $3 X_{2}(g) \rightarrow 2 X_{3}(g) .$ What are the sign of $\Delta H, \Delta S$ and $\Delta G$ for the reaction?
(a) +ve, +ve, +ve
(b) $+\mathrm{ve},-\mathrm{ve},-\mathrm{ve}$
(c) $-\mathrm{ve}_{,}+\mathrm{ve},-\mathrm{ve}$
(d) $-\mathrm{ve},-\mathrm{ve},-\mathrm{ve}$

Ajay Singhal

Numerade Educator

Problem 85

For the reaction $2 \mathrm{H}(g) \longrightarrow \mathrm{H}_{2}(g)$, the sign of $\Delta H$ and $\Delta S$ respectively are :
(a) $+,-$
(b) $+,+$
(c) $-,+$
(d) $-,-$

Ajay Singhal

Numerade Educator

Problem 86

Consider the following reaction.
$$
\mathrm{C}_{6} \mathrm{H}_{6}(l)+\frac{15}{2} \mathrm{O}_{2}(g) \longrightarrow 6 \mathrm{CO}_{2}(g)+3 \mathrm{H}_{2} \mathrm{O}(g)
$$
signs of $\Delta H, \Delta S$ and $\Delta G$ for the above reaction will be
(a) $+,-,+$
(b) -, +, -
(c) $-,+,+$
(d) $+,+,-$

Ajay Singhal

Numerade Educator

Problem 87

Consider the following reaction at temperature $T$ :
$$
\begin{aligned}
&\mathrm{CH}_{2}=\mathrm{CH}_{2}(g)+\mathrm{Cl}_{2}(g) \longrightarrow \mathrm{ClCH}_{2} \mathrm{CH}_{2} \mathrm{Cl}(g) \\
&\Delta_{r} H^{\circ}=-217.5 \mathrm{~kJ} / \mathrm{mol}, \quad \Delta_{r} S^{\circ}=-233.9 \mathrm{~J} / \mathrm{K}-\mathrm{mol}
\end{aligned}
$$
Reaction is supported by :
(a) entropy
(b) enthalpy
(c) both (a) \& (b)
(d) neither

Ajay Singhal

Numerade Educator

Problem 88

For a process to be spontaneous at constant $T$ and $P$ :
(a) $(\Delta G)_{\text {system }}$ must be negative
(b) $(\Delta G)_{\text {system }}$ must be positive
(c) $(\Delta S)_{\text {system }}$ must be positive
(d) $(\Delta S)_{\text {system }}$ must be negative

Ajay Singhal

Numerade Educator

Problem 89

For a reaction to occur spontaneously:
(a) $\Delta S$ must be negative
(b) $(-\Delta H+T \Delta S)$ must be positive
(c) $\Delta H+T \Delta S$ must be negative
(d) $\Delta H$ must be negative

Ajay Singhal

Numerade Educator

Problem 90

Which of the following conditions regarding a chemical process ensures its spontaneity at all temperature?
(a) $\Delta H>0, \Delta G<0$
(b) $\Delta H<0, \Delta S>0$
(c) $\Delta H<0, \Delta S<0$
(d) $\Delta H>0, \Delta S<0$

Ajay Singhal

Numerade Educator

Problem 91

The free energy change $\Delta G=0$, when
(a) the system is at equilibrium
(b) catalyst is added
(c) reactants are initially mixed thoroughly
(d) the reactants are completely consumed

Ajay Singhal

Numerade Educator

Problem 92

Which of the following conditions will always lead to a non-spontaneous, change?
(a) $\Delta H$ and $\Delta S$ both $+$ ve
(b) $\Delta H$ is -ve and $\Delta S$ is $+$ ve
(c) $\Delta H$ and $\Delta S$ both $-v e$
(d) $\Delta H$ is +ve and $\Delta S$ is -ve

Ajay Singhal

Numerade Educator

Problem 93

\begin{aligned}
&\text { Suppose that a reaction has } \Delta H=-40 \mathrm{~kJ} \text { and } \Delta S=-50 \mathrm{~J} / \mathrm{K} \text { . At what temperature range will it } \\
&\text { change from spontaneous to non-spontaneous? } \\
&\begin{array}{llll}
\text { (a) } 0.8 \mathrm{~K} \text { to } 1 \mathrm{~K} & \text { (b) } 799 \mathrm{~K} \text { to } 800 \mathrm{~K} & \text { (c) } 800 \mathrm{~K} \text { to } 801 \mathrm{~K} & \text { (d) } 799 \mathrm{~K} \text { to } 801 \mathrm{~K}
\end{array}
\end{aligned}

Ajay Singhal

Numerade Educator

Problem 94

For isothermal expansion in case of an ideal gas:
(a) $\Delta G=\Delta S$
(b) $\Delta G=\Delta H$
(c) $\Delta G=-T . \Delta S$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 95

What is the normal boiling point of mercury? Given : $\Delta H_{f}^{\circ}(\mathrm{Hg}, l)=0 ; S^{\circ}(\mathrm{Hg}, l)=77.4 \mathrm{~J} / \mathrm{K}-\mathrm{mol}$
$\Delta H_{f}^{\circ}(\mathrm{Hg}, g)=60.8 \mathrm{~kJ} / \mathrm{mol} ; \mathrm{S}^{\circ}(\mathrm{Hg}, g)=174.4 \mathrm{~J} / \mathrm{K}-\mathrm{mol}$
(a) $624.8 \mathrm{~K}$
(b) $626.8 \mathrm{~K}$
(c) $636.8 \mathrm{~K}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 96

$18 \mathrm{gm}$ of ice is converted into water at $0^{\circ} \mathrm{C}$ and $1 \mathrm{~atm}$. The entropies of $\mathrm{H}_{2} \mathrm{O}(s)$ and $\mathrm{H}_{2} \mathrm{O}(l)$ are $38.2$ and $60 \mathrm{~J} / \mathrm{mol} \mathrm{K}$ respectively. The enthalpy change for this conversion is :
(a) $5951.4 \mathrm{~J} / \mathrm{mol}$
(b) $595.14 \mathrm{~J} / \mathrm{mol}$
(c) $-5951.4 \mathrm{~J} / \mathrm{mol}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 97

Using the listed $\left[\Delta G^{\circ}{ }_{f}\right.$ values $]$ calculate $\Delta G^{\circ}$ for the reaction :
$3 \mathrm{H}_{2} \mathrm{~S}(g)[-33.6]+2 \mathrm{HNO}_{3}(l)[-80.6] \stackrel 2 \mathrm{NO}(g)[+86.6]+4 \mathrm{H}_{2} \mathrm{O}(l)[-237.1]+3 S(s)[0.0]$
(a) $-513.0$
(b) $-1037.0$
(c) $+433.4$
(d) $+225.0$

Ajay Singhal

Numerade Educator

Problem 98

Using the listed $\left[\Delta G^{\circ}{ }_{f}\right.$ values $]$ calculate $\Delta G^{\circ}$ for the reaction :
$3 \mathrm{H}_{2} \mathrm{~S}(g)[-33.6]+2 \mathrm{HNO}_{3}(l)[-80.6] \stackrel 2 \mathrm{NO}(g)[+86.6]+4 \mathrm{H}_{2} \mathrm{O}(l)[-237.1]+3 S(s)[0.0]$
(a) $-513.0$
(b) $-1037.0$
(c) $+433.4$
(d) $+225.0$

Ajay Singhal

Numerade Educator

Problem 99

Calculate $\Delta H_{f}^{\circ}$ for $\mathrm{UBr}_{4}$ from the $\Delta G^{\circ}$ of reaction and the $' S^{\circ}$ values.
$\mathrm{U}(s)+2 \mathrm{Br}_{2}(l) \longrightarrow \mathrm{UBr}_{4}(s) ; \quad \Delta G^{\circ}=-788.6 \mathrm{k} \mathrm{J} ; \quad S^{\circ}(\mathrm{J} / \mathrm{K}-\mathrm{mol}) 50.3,152.3,242.6$
(a) $-822.1 \mathrm{~kJ} / \mathrm{mol}$
(b) $-841.2 \mathrm{~kJ} / \mathrm{mol}$
(c) $-775.6 \mathrm{~kJ} / \mathrm{mol}$
(d) $-804.3 \mathrm{~kJ} / \mathrm{mol}$

Supratim Pal

Numerade Educator

Problem 100

The entropies of $\mathrm{H}_{2}(\mathrm{~g})$ and $\mathrm{H}(\mathrm{g})$ are $130.6$ and $114.6 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$ respectively at $298 \mathrm{~K}$. Using the data given below calculate the bond energy of $\mathrm{H}_{2}$ (in $\mathrm{kJ} / \mathrm{mol}$ ):
$\mathrm{H}_{2}(g) \longrightarrow 2 \mathrm{H}(g) ; \Delta G^{\circ}=406.6 \mathrm{~kJ}$
(a) $377.2$
(b) $436.0$
(c) $425.5$
(d) $430.5$

Ajay Singhal

Numerade Educator

Problem 101

The entropies of $\mathrm{H}_{2}(\mathrm{~g})$ and $\mathrm{H}(\mathrm{g})$ are $130.6$ and $114.6 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$ respectively at $298 \mathrm{~K}$. Using the data given below calculate the bond energy of $\mathrm{H}_{2}$ (in $\mathrm{kJ} / \mathrm{mol}$ ):
$\mathrm{H}_{2}(g) \longrightarrow 2 \mathrm{H}(g) ; \Delta G^{\circ}=406.6 \mathrm{~kJ}$
(a) $377.2$
(b) $436.0$
(c) $425.5$
(d) $430.5$

Supratim Pal

Numerade Educator

Problem 102

Which of the following option is correct?
(a) $\left[\frac{\partial \ln K_{p}}{\partial T}\right]=\frac{\Delta H^{\circ}}{R T^{2}}$.
*
(b) $\frac{\partial \ln K}{\partial T} \sum \frac{E_{a}}{\dot{R} T^{2}}$
(c) $\left[\frac{\partial \ln K_{p}}{\partial T}\right]=\frac{\Delta U}{R T^{2}}$
(d) All. of these $\ldots$.

Supratim Pal

Numerade Educator

Problem 103

Calculate $\Delta G^{\circ}(\mathrm{kJ} / \mathrm{mol})$ at $127^{\circ} \mathrm{C}$ for a reaction with $K_{\text {equilbrium }}=10^{5}$ :
(a) $-38.294$
(b) $-16.628$
(c) $-9.16$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 104

When reaction is carried out at standard states then at the equilibrium :
(a) $\Delta H^{\circ}=0$
(b) $\Delta S^{\circ}=0$
(c) equilibrium constant $K=0$
(d) equilibrium constant $K=1$

Ajay Singhal

Numerade Educator

Problem 105

At $25^{\circ} \mathrm{C}, \Delta G^{\circ}$ for the process $\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{H}_{2} \mathrm{O}(g)$ is $8.6 \mathrm{~kJ}$. The vapour pressure of water at this
remperature, is nearly : $\quad, \ldots, 4:$
(a) 24 torr
(b) 285 torr
(c) $32.17$ torr
(d) 100 torr

Ajay Singhal

Numerade Educator

Problem 106

For the auto-ionization of water. at $25^{\circ} \mathrm{C}, \mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{OH}^{-}(a q)$ equilibrium
constant is $10^{-14}$. What is $\Delta G^{\circ}$ for the process?
(a) $=8 \times 10^{4} \mathrm{~J}$
(b) $\simeq 3.5 \times .10^{4} \mathrm{~J}$
(c) $=10^{4}$ y
(d) None of these
1.

Ajay Singhal

Numerade Educator

Problem 107

The molar entropies of $\mathrm{HI}(g), \mathrm{H}(g)$ and $\mathrm{I}(g)$ at $298 \mathrm{~K}$ are $206.5,114.6$, and $180.7 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$
respectively. Using the $\Delta G^{\circ}$ given below, calculate the bond energy of HI. $\mathrm{HI}(g) \longrightarrow \mathrm{H}(g)+\mathrm{I}(g) ; \quad \Delta G^{\circ}=271.8 \mathrm{~kJ}$
(a) $282.4$
(b) $298.3$
(c) $290.1$
(d) $315.4$

Ajay Singhal

Numerade Educator

Problem 108

Hess's law states that :
(a) the standard enthalpy of an overall reaction is the sum of the enthalpy changes in individual reactions.
(b) enthalpy of formation of a compound is same as the enthalpy of decomposition of the compound into constituent elements, but with opposite sign.
(c) at constant temperature the pressure of a gas is inversely h proportional to its volume
(d) the mass of a gas dissolved per litre of a solvent is proportional to the pressure of the gas in equilibrium with the solution

Ajay Singhal

Numerade Educator

Problem 109

An imaginary reaction $X \longrightarrow Y$ takes place in three steps $X \longrightarrow A, \Delta H=-q_{1} ; \quad B \longrightarrow A, \Delta H=-q_{2} ; \quad B \longrightarrow Y, \Delta H=-q_{3}$
If Hess' law is applicable, then the heat of the reaction $(X \rightarrow Y)$ is :
(a) $q_{1}-q_{2}+q_{3}$
(b) $q_{2}-q_{3}-q_{1}$
(c) $q_{1}-q_{2}-q_{3}$
(d) $q_{3}-q_{2}-q_{1}$

Ajay Singhal

Numerade Educator

Problem 110

The enthalpy change for a reaction does not depend upon :
(a) the physical states of reactants and products
(b) use of different reactants for the same product
(c) the number of intermediate reaction steps
(d) the differences in initial or final temperatures of involved substances

Ajay Singhal

Numerade Educator

Problem 111

The standard enthalpy of formation of gaseous $\mathrm{H}_{2} \mathrm{O}$ at $298 \mathrm{~K}$ is $-241.82 \mathrm{~kJ} / \mathrm{mol} .$ Calculate $\Delta H^{\circ}$ at $373 \mathrm{~K}$ given the following values of the molar heat capacities at constant pressure :
$\mathrm{H}_{2} \mathrm{O}(g)=33.58 \mathrm{JK}^{-1} \mathrm{~mol}^{-1} ; \mathrm{H}_{2}(g)=29.84 \mathrm{JK}^{-1} \mathrm{~mol}^{-1} ; \mathrm{O}_{2}(g)=29.37 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$
Assume that the heat capacities are independent of temperature :
(a) $-242.6 \mathrm{~kJ} / \mathrm{mol}$
(b) $-485.2 \mathrm{~kJ} / \mathrm{mol}$
(c) $-121.3 \mathrm{~kJ} / \mathrm{mol}$
(d) $-286.4 \mathrm{~kJ} / \mathrm{mol}$

Ajay Singhal

Numerade Educator

Problem 113

For which of the following substances the enthalpy of formation in the standard state is zero?
(a) Sucrose
(b) Ethanol
(c) Aluminium
(d) Calcium chloride

Ajay Singhal

Numerade Educator

Problem 114

Calculate the standard enthalpy of reaction for the following reaction using the listed enthalpies of reaction :
$$
\begin{aligned}
3 \mathrm{Co}(s)+2 \mathrm{O}_{2}(g) & \longrightarrow \mathrm{Co}_{3} \mathrm{O}_{4}(s) \\
2 \mathrm{Co}(s)+\mathrm{O}_{2}(g) & \longrightarrow 2 \mathrm{CoO}(s) ; \quad \Delta H_{1}^{\circ}=-475.8 \mathrm{~kJ} \\
6 \mathrm{CoO}(s)+\mathrm{O}_{2}(g) & \longrightarrow 2 \mathrm{Co}_{3} \mathrm{O}_{4}(s) ; \Delta H_{2}^{\circ}=-355.0 \mathrm{~kJ}
\end{aligned}
$$
(a) $-891.2 \mathrm{~kJ}$
(b) $-120.8 \mathrm{~kJ}$
(c) $+891.2 \mathrm{~kJ}$
(d) $-830.8 \mathrm{~kJ}$

Ajay Singhal

Numerade Educator

Problem 115

From given following equations and $\Delta H^{\circ}$ values, determine the enthalpy of reaction at $298 \mathrm{~K}$ for the reaction :
$$
\begin{aligned}
\mathrm{C}_{2} \mathrm{H}_{4}(g)+6 \mathrm{~F}_{2}(g) & \longrightarrow 2 \mathrm{CF}_{4}(g)+4 \mathrm{HF}(g) \\
\mathrm{H}_{2}(g)+\mathrm{F}_{2}(g) & \longrightarrow 2 \mathrm{HF}(g) ; \quad \Delta H_{1}^{\circ}=-537 \mathrm{~kJ}
\end{aligned}
$$
$\mathrm{C}(s)+2 \mathrm{~F}_{2}(g) \longrightarrow \mathrm{CF}_{4}(g) ; \quad \Delta H_{2}^{\circ}=-680 \mathrm{~kJ}$
$\mathrm{ZC}(s)+2 \mathrm{H}_{2}(g) \longrightarrow \mathrm{C}_{2} \mathrm{H}_{4}(g) ; \Delta H_{3}^{\circ}=52 \mathrm{~kJ}$
(a) $-1165$
(b) $-2486$
(c) $+1165$
(d) $+2486$

Ajay Singhal

Numerade Educator

Problem 116

Given :
$\mathrm{C}($ diamond $)+\mathrm{O}_{2} \longrightarrow \mathrm{CO}_{2} ; \Delta H=-395 \mathrm{~kJ}$
$\mathrm{C}$ (graphite) $+\mathrm{O}_{2} \longrightarrow \mathrm{CO}_{2} ; \Delta H=-393 \mathrm{~kJ}$
The enthalpy of formation of diamond from graphite is
(a) $+2.0 \mathrm{~kJ}$
(b) $-1.5 \mathrm{~kJ}$
(c) $-788 \mathrm{~kJ}$
(d) $788 \mathrm{~kJ}$

Ajay Singhal

Numerade Educator

Problem 117

Which of the following equations represents a reaction that provides the enthalpy of formation of $\mathrm{CH}_{3} \mathrm{Cl}$ ?
(a) $\mathrm{C}(s)+\mathrm{HCl}(g)+\mathrm{H}_{2}(g) \longrightarrow \mathrm{CH}_{3} \mathrm{Cl}(g)$
(b) $\mathrm{C}(\mathrm{s})+3 \mathrm{H}(\mathrm{g})+\mathrm{Cl}(\mathrm{g}) \longrightarrow \mathrm{CH}_{3} \mathrm{Cl}(g)$
(c) $\mathrm{C}(s)+3 / 2 \mathrm{H}_{2}(g)+1 / 2 \mathrm{Cl}_{2}(g) \longrightarrow \mathrm{CH}_{3} \mathrm{Cl}(g)$
(d) $\mathrm{CH}_{4}(g)+\mathrm{Cl}_{2}(g) \longrightarrow \mathrm{CH}_{3} \mathrm{Cl}(g)+\mathrm{HCl}(g)$

Ajay Singhal

Numerade Educator

Problem 118

Use the given standard enthalpies of formation (in $\mathrm{kJ} / \mathrm{mol}$ ) to determine the enthalpy of reaction of the following reaction :
$$
\begin{gathered}
\mathrm{NH}_{3}(g)+3 \mathrm{~F}_{2}(g) \longrightarrow \mathrm{NF}_{3}(g)+3 \mathrm{HF}(g) \\
\Delta H_{f}^{\circ}\left(\mathrm{NH}_{3}, g\right)=-46.2 ; \quad \Delta H_{f}^{\circ}\left(\mathrm{NF}_{3}, g\right)=-113.0 ; \quad \Delta H_{f}^{\circ}(\mathrm{HF}, g)=-269.0
\end{gathered}
$$
1.T/mnl
(h) $-8738 \mathrm{~kJ} / \mathrm{mol}$
(c) $-697.2 \mathrm{~kJ} / \mathrm{mol}$
(d) $-890.4 \mathrm{~kJ} / \mathrm{mol}$

Ajay Singhal

Numerade Educator

Problem 119

The standard enthalpy of formation of octane $\left(\mathrm{C}_{8} \mathrm{H}_{18}\right)$ is $-250 \mathrm{~kJ} / \mathrm{mol}$. Calculate the enthalpy of combustion of $\mathrm{C}_{8} \mathrm{H}_{18}$. The enthalpy of formation of $\mathrm{CO}_{2}(g)$ and $\mathrm{H}_{2} \mathrm{O}(l)$ are $-394 \mathrm{~kJ} / \mathrm{mol}$ and $-286 \mathrm{~kJ} / \mathrm{mol}$ respectively :
(a) $-5200 \mathrm{~kJ} / \mathrm{mol}$
(b) $-5726 \mathrm{~kJ} / \mathrm{mol}$
(c) $-5476 \mathrm{~kJ} / \mathrm{mol}$
(d) $-5310 \mathrm{~kJ} / \mathrm{mol}$

Ajay Singhal

Numerade Educator

Problem 120

Determine the enthalpy of formation of $\mathrm{B}_{2} \mathrm{H}_{6}(g)$ in $\mathrm{kJ} / \mathrm{mol}$ of the following reaction.
$$
\mathrm{B}_{2} \mathrm{H}_{6}(g)+3 \mathrm{O}_{2}(g) \longrightarrow \mathrm{B}_{2} \mathrm{O}_{3}(s)+3 \mathrm{H}_{2} \mathrm{O}(g)
$$
Given : $\Delta_{r} H^{\circ}=-1941 \cdot \mathrm{kJ} / \mathrm{mol} ; \quad \Delta H_{f}^{\circ}\left(\mathrm{B}_{2} \mathrm{O}_{3}, s\right)=-1273 \mathrm{~kJ} / \mathrm{mol}$
$\mathrm{W}_{f}^{\circ}\left(\mathrm{H}_{2} \mathrm{O}, g\right)=-241.8 \mathrm{~kJ} / \mathrm{mol}$
(a) $-75.6$
(b) $+7 \overline{5} .6$
(c) $-57.4$
(d) $-28.4$

Ajay Singhal

Numerade Educator

Problem 121

Consider the following reactions:
$$
\begin{aligned}
\mathrm{C}(s)+\mathrm{O}_{2}(g) & \longrightarrow \mathrm{CO}_{2}(g)+x \mathrm{~kJ} \\
\mathrm{CO}(g)+\frac{1}{2} \mathrm{O}_{2}(g) & \longrightarrow \mathrm{CO}_{2}(g)+y \mathrm{~kJ}
\end{aligned}
$$
The heat of formation of $\mathrm{CO}(g)$ is :
(a) $-(x+y) \mathrm{kJ} / \mathrm{mol}$
(b) $(x-y) \mathrm{kJ} / \mathrm{mol}$
(c) $(y-x) \mathrm{kJ} / \mathrm{mol}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 122

If $\Delta_{f} H^{\circ}\left(\mathrm{C}_{2} \mathrm{H}_{4}\right)$ and $\Delta_{f} H^{\circ}\left(\mathrm{C}_{2} \mathrm{H}_{6}\right)$ are $x_{1}$ and $x_{2} \mathrm{kcal} \mathrm{mol}^{-1}$, then heat of hydrogenation of
$\mathrm{C}_{2} \mathrm{H}_{4}$ is :
(a) $x_{1}+x_{2}$
(b) $x_{1}-x_{2}$
(c) $x_{2}-x_{1}$
(d) $x_{1}+2 x_{2}$

Ajay Singhal

Numerade Educator

Problem 123

What amount of energy $(\mathrm{kJ})$ is released in the combustion of $5.8 \mathrm{~g}$ of $\mathrm{C}_{4} \mathrm{H}_{10}(\mathrm{~g})$ ? $2 \mathrm{C}_{4} \mathrm{H}_{10}(g)+13 \mathrm{O}_{2}(g) \longrightarrow 8 \mathrm{CO}_{2}(g)+10 \mathrm{H}_{2} \mathrm{O}(l) ; \quad \Delta H^{\circ}=-5756 \mathrm{~kJ}$
(a) $575.6$
(b) $287.8$
(c) 182
(d) $57.56$

Ajay Singhal

Numerade Educator

Problem 124

The enthalpy of the reaction forming $\mathrm{PbO}$ according to the following equation is $438 \mathrm{~kJ}$. What heat energy (kJ) is released in formation of $22.3 \mathrm{~g} \mathrm{PbO}(s)$ ? (Atomic weights : $\mathrm{Pb}=207, \mathrm{O}=16.0$ )
$$
2 \mathrm{~Pb}(s)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{PbO}(s)
$$
(a) $21.9$
(b) $28.7$
(c) $14.6$
(d) $34.2$

Ajay Singhal

Numerade Educator

Problem 125

The fat, $\mathrm{C}_{57} \mathrm{H}_{104} \mathrm{O}_{6}(\mathrm{~s})$, is metabolized via the following reaction. Given the enthalpies of formation, calculate the energy $(\mathrm{kJ})$ liberated when $1.0 \mathrm{~g}$ of this fat reacts.
$$
\begin{gathered}
\mathrm{C}_{57} \mathrm{H}_{104} \mathrm{O}_{6}(\mathrm{~s})+80 \mathrm{O}_{2}(g) \longrightarrow 57 \mathrm{CO}_{2}(g)+52 \mathrm{H}_{2} \mathrm{O}(l) \\
\Delta_{f} H^{\circ}\left(\mathrm{C}_{57} \mathrm{H}_{104} \mathrm{O}_{6}, s\right)=-70870 \mathrm{~kJ} / \mathrm{mol} ; \Delta_{f} H^{\circ}\left(\mathrm{H}_{2} \mathrm{O}, l\right)=-285.8 \mathrm{~kJ} / \mathrm{mol} ; \\
\triangle_{f} H^{\circ}\left(\mathrm{CO}_{2}, g\right)=-393.5 \mathrm{~kJ} / \mathrm{mol}
\end{gathered}
$$
(a) $-37.98$
(b) $-40.4$
(c) $-33.4$
(d) $-30.2$ be $-1$

Ajay Singhal

Numerade Educator

Problem 126

The heat of formation of $\mathrm{NH}_{3}(g)$ is $-46 \mathrm{~kJ} \mathrm{~mol}^{-1}$. The $\Delta H$ (in $\mathrm{kJ} \mathrm{mol}^{-1}$ ) of the reaction, $2 \mathrm{NH}_{3}(g) \longrightarrow \mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(g)$ is :
(a) 46
(b) $-46$
(c) 92
(d) $-92$

Ajay Singhal

Numerade Educator

Problem 127

Consider the following reaction:
$$
\begin{aligned}
\mathrm{H}_{2} \mathrm{O}(l) & \longrightarrow \mathrm{H}_{2} \mathrm{O}(g) ; \Delta H_{1}=44 \mathrm{~kJ} \\
2 \mathrm{CH}_{3} \mathrm{OH}(l)+3 \mathrm{O}_{2}(g) & \longrightarrow 4 \mathrm{H}_{2} \mathrm{O}(l)+2 \mathrm{CO}_{2}(g) ; \Delta H_{2}=-1453 \mathrm{~kJ}
\end{aligned}
$$
What is the value of $\Delta H$ for second reaction if water vapour instead of liquid water is formed as product?
(a) $-1409 \mathrm{~kJ}$
(b) $-1629 \mathrm{~kJ}$
(c) $-1277 \mathrm{~kJ}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 128

The standard enthalpy change for the following reaction is $436.4 \mathrm{~kJ}:$
$$
\mathrm{H}_{2}(g) \longrightarrow \mathrm{H}(g)+\mathrm{H}(g)
$$
What is the $\Delta_{f} H^{\circ}$ of atomic hydrogen $(\mathrm{H}) ?$
(a) $872.8 \mathrm{~kJ} / \mathrm{mol}$
(b) $218.2 \mathrm{~kJ} / \mathrm{mol}$
(c) $-218.2 \mathrm{~kJ} / \mathrm{mol}$
(d) $-436.9 \mathrm{~kJ} / \mathrm{mo}$
Determine enthalpy of formation for $\mathrm{H}_{2} \mathrm{O}_{2}(l)$, using listed enthalpies of reaction :

Ajay Singhal

Numerade Educator

Problem 129

Determine enthalpy of formation for $\mathrm{H}_{2} \mathrm{O}_{2}(l)$, using listed enthalpies of reaction :
$$
\begin{aligned}
\mathrm{N}_{2} \mathrm{H}_{4}(l)+2 \mathrm{H}_{2} \mathrm{O}_{2}(l) & \longrightarrow \mathrm{N}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(l) ; & \Delta_{r} H_{1}^{\circ}=-818 \mathrm{~kJ} / \mathrm{mol} \\
\mathrm{N}_{2} \mathrm{H}_{4}(l)+\mathrm{O}_{2}(g) & \longrightarrow \mathrm{N}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(l) ; & \Delta_{r} H_{2}^{\circ}=-622 \mathrm{~kJ} / \mathrm{mol} \\
\mathrm{H}_{2}(g)+1 / 2 \mathrm{O}_{2}(g) & \Delta_{r} H_{3}^{\circ}=-285 \mathrm{~kJ} / \mathrm{mol}
\end{aligned}
$$
(a) $-383 \mathrm{~kJ} / \mathrm{mol}$
(b) $-187 \mathrm{~kJ} / \mathrm{mol}$
(c) $-498 \mathrm{~kJ} / \mathrm{mol}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 131

Stearic acid $\left[\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{16} \mathrm{CO}_{2} \mathrm{H}\right]$ is a fatty acid, the part of fat that stores most of the energy. $1.0 \mathrm{~g}$ of stearic acid was burned in a bomb calorimeter. The bomb had a heat capacity of 652 $\mathrm{~J} /{ }^{\circ} \mathrm{C} .$ If the temperature of $500 \mathrm{~g}$ water $\left(c=4.18 \mathrm{~J} / \mathrm{g}^{\circ} \mathrm{C}\right)$ rose from $25.0$ to $39.3^{\circ} \mathrm{C}$, how much heat was released when the stearic acid was burned? $\left[\right.$ Given $\left.C_{p}\left(\mathrm{H}_{2} \mathrm{O}\right)=4.18 \mathrm{~J} / \mathrm{g}^{\circ} \mathrm{C}\right]$
(a) $39.21 \mathrm{~kJ}$
(b) $29.91 \mathrm{~kJ}$
(c) $108 \mathrm{~kJ}$
$\begin{array}{llll}\text { (d) } 9.32 \mathrm{~kJ} & \therefore \therefore\end{array}$

Ajay Singhal

Numerade Educator

Problem 132

Gasoline has an enthalpy of combustion $24000 \mathrm{~kJ} /$ gallon. When gasoline burns in an automobile engine, approximately $30 \%$ of the energy released is used to produce mechanical work. The remainder is lost as heat transfer to the engine's cooling system. As a start on estimating how much heat transfer is required, calculate what mass of water could be heated from $25^{\circ} \mathrm{C}$ to $75^{\circ} \mathrm{C}$ by the combustion of $1.0$ gallon of gasoline in an automobile? (Given : $\left.\mathrm{C}\left(\mathrm{H}_{2} \mathrm{O}\right)=4.18 \mathrm{~J} / \mathrm{g}^{\circ} \mathrm{C}\right)$

Ajay Singhal

Numerade Educator

Problem 133

A $0.05 \mathrm{~L}$ sample of $0.2 \mathrm{M}$ aqueous hydrochloric acid is added to $0.05 \mathrm{~L}$ of $0.2 \mathrm{M}$ aqueous ammonia in a calorimeter. Heat capacity of entire calorimeter system is $480 \mathrm{~J} / \mathrm{K}$. The temperature increase is $1.09 \mathrm{~K}$. Calculate $\Delta_{r} H^{\circ}$ in $\mathrm{kJ} / \mathrm{mol}$ for the following reaction:
$$
\mathrm{HCl}(a q .)+\mathrm{NH}_{3}(a q) \longrightarrow \mathrm{NH}_{4} \mathrm{Cl}(a q)
$$
(a) $-52.32$
(b) $-61.1$
(c) $-55.8$
(d) $-58.2$

Ajay Singhal

Numerade Educator

Problem 134

A coffee cup calorimeter initially contains $125 \mathrm{~g}$ of water, at a temperature of $24.2^{\circ} \mathrm{C} .8 \mathrm{~g}$ of ammonium nitrate $\left(\mathrm{NH}_{4} \mathrm{NO}_{3}\right)$, also at $24.2^{\circ} \mathrm{C}$, is added to the water, and the final temperature is $18.2^{\circ} \mathrm{C}$. What is the heat of solution of ammonium nitrate in $\mathrm{kJ} / \mathrm{mol}$ ? The specific heat capacity of the solution is $4.2 \mathrm{~J} /{ }^{\circ} \mathrm{C} \mathrm{g}$.
(a) $33.51 \mathrm{~kJ} / \mathrm{mol}$
(b) $39.5 \mathrm{~kJ} / \mathrm{mol}$
(c) $32.2 \mathrm{~kJ} / \mathrm{mol}$
(d) $37.3 \mathrm{~kJ} / \mathrm{mol}$

Ajay Singhal

Numerade Educator

Problem 135

Read following statement(s) carefully and select the right option :
(I) The enthalpy of solution of $\mathrm{CaCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}$ in a large volume of water is endothermic to the extent of $3.5 \mathrm{kcal} /$ mol. If $\Delta H=-23.2 \mathrm{kcal}$ for the reaction,
$$
\mathrm{CaCl}_{2}(s)+6 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{CaCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}(s)
$$
then heat of solution of $\mathrm{CaCl}_{2}$ (anhydrous) in a large volume of water is $-19.7 \mathrm{kcal} / \mathrm{mol}$
(II) For the reaction $2 \mathrm{Cl}(g) \rightarrow \mathrm{Cl}_{2}(g)$; the sign of $\Delta H$ and $\Delta S$ are negative.
(a) statement $\mathrm{I}$ and $\mathrm{II}$ both are wrong
(b) both are correct
(c) only I is correct
(d) only II is correct

Ajay Singhal

Numerade Educator

Problem 136

If the enthalpy of formation and enthalpy of solution of $\mathrm{HCl}(g$ ) are $-92.3 \mathrm{~kJ} / \mathrm{mol}$ and $-75.14$ $\mathrm{kJ} / \mathrm{mol}$ respectively then find enthalpy of formation of $\mathrm{Cl}^{-}(a q):$
(a) $-17.16 \mathrm{~kJ} / \mathrm{mol}$
(b) $-167.44 \mathrm{~kJ} / \mathrm{mol}$
(c) $17.16 \mathrm{~kJ} / \mathrm{mol}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 137

At $25^{\circ} \mathrm{C}, 1$ mole of $\mathrm{MgSO}_{4}$ was dissolved in water, the heat evolved was found to be $91.2 \mathrm{~kJ}$. One mole of $\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}$ on dissolution gives a solution of the same composition accompanied by an absorption of $13.8 \mathrm{~kJ}$. The enthalpy of hydration, i.e., $\Delta H$ for the reaction
$$
\mathrm{MgSO}_{4}(s)+7 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}(s) \text { is : }
$$
(a) $-105 \mathrm{~kJ} / \mathrm{mol}$
(b) $-77.4 \mathrm{~kJ} / \mathrm{mol}$
(c) $105 \mathrm{~kJ} / \mathrm{mol}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 138

The enthalpies of neutralization of a weak base $A O H$ and a strong base $B O H$ by $H C l$ are $-12250 \mathrm{cal} / \mathrm{mol}$ and $-13000 \mathrm{cal} / \mathrm{mol}$ respectively. When one mole of $\mathrm{HCl}$ is added to a solution containing 1 mole of $A \mathrm{OH}$ and 1 mole of $B O H$, the enthalpy change was $-12500 \mathrm{cal} /$ mol. In what ratio is the acid distribution between $A O H$ and $B O H ?$
(a) $2: 1$
(b) $2: 3$
(c) $1: 2$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 139

The magnitude of enthalpy change for neutralization of the reaction ; $\mathrm{MgO}(s)+2 \mathrm{HCl}(a q) \longrightarrow \mathrm{MgCl}_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \quad$ (Given $\mathrm{H}^{+}(a q)+\mathrm{OH}^{-}(a q) \longrightarrow \mathrm{H}_{2} \mathrm{O}(l) ;-57$
$\mathrm{kJ} / \mathrm{mol}$ ) will be :

Ajay Singhal

Numerade Educator

Problem 140

Enthalpy of neutralization of $\mathrm{HCl}$ by $\mathrm{NaOH}$ is $-55.84 \mathrm{~kJ} / \mathrm{mol}$ and by $\mathrm{NH}_{4} \mathrm{OH}$ is $-51.34 \mathrm{~kJ} / \mathrm{mol}$. The enthalpy of ionization of $\mathrm{NH}_{4} \mathrm{OH}$ is :
(a) $107.18 \mathrm{~kJ} / \mathrm{mol}$
(b) $4.5 \mathrm{~kJ} / \mathrm{mol}$
(c) $-4.5 \mathrm{~kJ} / \mathrm{mol}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 141

Which of the following reaction is endothermic?
(a) $\mathrm{CaCO}_{3} \longrightarrow \mathrm{CaO}+\mathrm{CO}_{2}$
(b) $\mathrm{Fe}+\mathrm{S} \rightarrow \longrightarrow \mathrm{FeS}$
(c) $\mathrm{NaOH}+\mathrm{HCl} \longrightarrow \mathrm{NaCl}+\mathrm{H}_{2} \mathrm{O}$
(d) $\mathrm{CH}_{4}+2 \mathrm{O}_{2} \longrightarrow \mathrm{CO}_{2}+2 \mathrm{H}_{2} \mathrm{O}$

Ajay Singhal

Numerade Educator

Problem 142

Which of the following is not correct?
(a) Dissolution of $\mathrm{NH}_{4} \mathrm{Cl}$ in excess of water is an endothermic process
(b) Neutralisation is always exothermic
(c) The absolute value of enthalpy (H) can be determined experimentally
(d) The heat of reaction at constant volume is denoted by $\Delta E$

Ajay Singhal

Numerade Educator

Problem 143

Substance $A_{2} B(g$ ) can undergoes decomposition to form two set of products :
If the molar ratio of $A_{2}(g)$ to $A(g)$ is $5: 3$ in a set of product gases, then the energy involved in the decomposition of 1 mole of $A_{2} B(g)$ is :
(a) $48.75 \mathrm{~kJ} / \mathrm{mol}$
(b) $43.73 \mathrm{~kJ} / \mathrm{mol}$
(c) $46.25 \mathrm{~kJ} / \mathrm{mol}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 144

Boron can undergo the following reactions with the given enthalpy changes:
$$
\begin{aligned}
&2 \mathrm{~B}(s)+\frac{3}{2} \mathrm{O}_{2}(g) \longrightarrow \mathrm{B}_{2} \mathrm{O}_{3}(s) ; \quad \Delta H=-1260 \mathrm{~kJ} \\
&2 \mathrm{~B}(s)+3 \mathrm{H}_{2}(g) \longrightarrow \mathrm{B}_{2} \mathrm{H}_{6}(g) ; \Delta H=30 \mathrm{~kJ}
\end{aligned}
$$
Assume no other reactions are occurring. If in a container (operating at constant pressure) which is isolated from the surrounding, mixture of $\mathrm{H}_{2}$ (gas) and $\mathrm{O}_{2}$ (gas) are passed over excess of $\mathrm{B}(s)$, then calculate the molar ratio $\left(\mathrm{O}_{2}: \mathrm{H}_{2}\right)$ so that temperature of the container do not change :
(a) $15: 3$
(b) $42: 1$
(c) $1: 42$
(d) $1: 84$

Ajay Singhal

Numerade Educator

Problem 145

The enthalpy change for the following reaction is $368 \mathrm{~kJ}$. Calculate the average $\mathrm{O}-\mathrm{F}$ bond energy.
$$
\mathrm{OF}_{2}(g) \longrightarrow \mathrm{O}(g)+2 \mathrm{~F}(g)
$$
(a) $184 \mathrm{~kJ} / \mathrm{mol}$
(b) $368 \mathrm{~kJ} / \mathrm{mol}$
(c) $536 \mathrm{~kJ} / \mathrm{mol}$
(d) $736 \mathrm{~kJ} / \mathrm{mol}$

Ajay Singhal

Numerade Educator

Problem 146

The enthalpy change for the reaction, $\mathrm{C}_{2} \mathrm{H}_{6}(g) \longrightarrow 2 \mathrm{C}(\mathrm{g})+6 \mathrm{H}(\mathrm{g})$ is $\mathrm{X} \mathrm{kJ} .$ The bond energy
of $\mathrm{C}-\mathrm{H}$ bond is :
(a) $\frac{X}{2}$
(b) $\frac{X}{3}$
(c) $\frac{X}{6}$
(d) data insufficient

Ajay Singhal

Numerade Educator

Problem 147

The table given below lists the bond dissociation energy $\left(E_{\mathrm{diss}}\right)$ for single covalent bonds formed between $\mathrm{C}$ and atoms $\mathrm{A}, \mathrm{B}, \mathrm{D}, \mathrm{E}$. Bond $E_{\text {diss }}\left(\mathrm{kcal} \mathrm{mol}^{-1}\right)$
$\mathrm{C}-\mathrm{A}$
240
$\mathrm{C}-\mathrm{B}$
382
$\mathrm{C}-\mathrm{D}$
276
$\mathrm{C}-\mathrm{E}$
486
Which of the atoms has smallest size ?
(a) D
(b) $\mathrm{E}$
(c) $\mathrm{A}$
(d) $\mathrm{D}$

Ajay Singhal

Numerade Educator

Problem 148

Calculate $\mathrm{P}-\mathrm{Cl}$ bond enthalpy Given : $\Delta_{f} H\left(\mathrm{PCl}_{3}, g\right)=306 \mathrm{~kJ} / \mathrm{mol} ; \quad \Delta H_{\text {atomization }}(\mathrm{P}, s)=314 \mathrm{~kJ} / \mathrm{mol}$;
$\Delta_{f} \mathrm{H}(\mathrm{Cl}, g)=121 \mathrm{~kJ} / \mathrm{mol}$
(a) $123.66 \mathrm{~kJ} / \mathrm{mol}$
(b) $371 \mathrm{~kJ} / \mathrm{mol}$
(c) $19 \mathrm{~kJ} / \mathrm{mol}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 149

Calculate the enthalpy for the following reaction using the given bond energies $(\mathrm{kJ} / \mathrm{mol}):$ $(C-H=414 ; H-O=463 ; H-C l=431, C-C l=326 ; C-O=335)$
$\mathrm{CH}_{3}-\mathrm{OH}(g)+\mathrm{HCl}(g) \longrightarrow \mathrm{CH}_{3}-\mathrm{Cl}(g)+\mathrm{H}_{2} \mathrm{O}(g)$
(a) $-23 \mathrm{~kJ} / \mathrm{mol}$
(b) $-42 \mathrm{~kJ} / \mathrm{mol}$
(c) $-59 \mathrm{~kJ} / \mathrm{mol}$
(d) $-511 \mathrm{~kJ} / \mathrm{mol}$

Ajay Singhal

Numerade Educator

Problem 150

Based on the values of B.E. given, $\Delta_{f} H^{\circ}$ of $\mathrm{N}_{2} \mathrm{H}_{4}(g)$ is :
Given : $\mathrm{N}-\mathrm{N}=159 \mathrm{~kJ} \mathrm{~mol}^{-1} ; \mathrm{H}-\mathrm{H}=436 \mathrm{~kJ} \mathrm{~mol}^{-1}$
$\mathrm{N} \equiv \mathrm{N}=941 \mathrm{~kJ} \mathrm{~mol}^{-1} ; \mathrm{N}-\mathrm{H}=398 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(a) $711 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(b) $62 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(c) $-98 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(d) $-711 \mathrm{~kJ} \mathrm{~mol}^{-1}$

Ajay Singhal

Numerade Educator