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43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

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Chapter 1

Some Basic Concepts of Chemistry - all with Video Answers

Educators

Section 1

Topic 1 : Measurement , Mole Concept and Percentage Composition

02:38

Problem 1

A solution of two components containing $n_{1}$ moles of the $1^{\text {st }}$ component and $n_{2}$ moles of the $2^{\text {nd }}$ component is prepared. $\mathrm{M}_{1}$ and $\mathrm{M}_{2}$ are the molecular weights of component 1 and 2 respectively. If $d$ is the density of the solution in $g \mathrm{~mL}^{-1}, \mathrm{C}_{2}$ is the molarity and $x_{2}$ is the mole fraction of the $2^{\text {nd }}$ component, then $\mathrm{C}_{2}$ can be expressed as:
[Main Sep. 06, 2020 (I)]
(a) $\mathrm{C}_{2}=\frac{1000 x_{2}}{\mathrm{M}_{1}+x_{2}\left(\mathrm{M}_{2}-\mathrm{M}_{1}\right)}$
(b) $\mathrm{C}_{2}=\frac{d x_{2}}{\mathrm{M}_{2}+x_{2}\left(\mathrm{M}_{2}-\mathrm{M}_{1}\right)}$
(c) $\mathrm{C}_{2}=\frac{1000 d x_{2}}{\mathrm{M}_{1}+x_{2}\left(\mathrm{M}_{2}-\mathrm{M}_{1}\right)}$
(d) $\mathrm{C}_{2}=\frac{d x_{1}}{\mathrm{M}_{2}+x_{2}\left(\mathrm{M}_{2}-\mathrm{M}_{1}\right)}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:26

Problem 2

The average molar mass of chlorine is $35.5 \mathrm{~g} \mathrm{~mol}^{-1}$. The ratio of ${ }^{35} \mathrm{Cl}$ to ${ }^{37} \mathrm{Cl}$ in naturally occrring chlorine is close to:(a) 4: 1
(b) $3: 1$
(c) $2: 1$
(d) $1: 1$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:20

Problem 3

Amongst the following statements, that which was not proposed by Dalton was:
[Main Jan. 07, 2020 (I)]
(a) Chemical reactions involve reorganization of atoms. These are neither created nor destroyed in a chemical reaction.
(b) All the atoms of a given element have identical properties including identical mass. Atoms of different elements differ in mass.
(c) When gases combine or reproduced in a chemical reaction they do so in a simple ratio by volume provided all gases are at the same $\mathrm{T}$ $\& \mathrm{P}$.
(d) Matter consists of indivisible atoms.

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:47

Problem 4

$8 \mathrm{~g}$ of $\mathrm{NaOH}$ is dissolved in $18 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O} .$ Mole fraction of $\mathrm{NaOH}$ in solution and molality (in mol $\mathrm{kg}^{-1}$ ) of the solution respectively are :
[Main Jan. 12, 2019 (II)]
(a) $0.2,22.20$
(b) $0.2,11.11$
(c) $0.167,11.11$
(d) $0.167,22.20$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:42

Problem 5

The amount of sugar $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$ required to prepare $2 \mathrm{~L}$ of its $0.1 \mathrm{M}$ aqueous solution is:
[Main Jan. 10, 2019 (II)]
(a) $136.8 \mathrm{~g}$
(b) $17.1 \mathrm{~g}$
(c) $68.4 \mathrm{~g}$
(d) $34.2 \mathrm{~g}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:38

Problem 6

The ratio of mass percent of $\mathrm{C}$ and $\mathrm{H}$ of an organic compound $\left(\mathrm{C}_{\mathrm{X}} \mathrm{H}_{\mathrm{Y}} \mathrm{O}_{\mathrm{Z}}\right)$ is $6: 1$. If one molecule of the above compound $\left(\mathrm{C}_{\mathrm{X}} \mathrm{H}_{\mathrm{Y}} \mathrm{O}_{\mathrm{Z}}\right)$
contains half as much oxygen as required to burn one molecule ofcompound $\mathrm{C}_{\mathrm{X}} \mathrm{H}_{\mathrm{Y}}$ completely to $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$. The empirical formula of compound $\mathrm{C}_{\mathrm{X}} \mathrm{H}_{\mathrm{Y}} \mathrm{O}_{\mathrm{Z}}$ is :
[Main 2018]
(a) $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}_{3}$
(b) $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}$
(c) $\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{O}_{2}$
(d) $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}_{3}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:01

Problem 7

An unknown chlorohydrocarbon has $3.55 \%$ of chlorine. If each molecule of the hydrocarbon has one chlorine atom only, chlorine atoms present in $1 \mathrm{~g}$ of chlorohydrocarbon are:
(Atomic wt. of $\mathrm{Cl}=35.5 \mathrm{u}$; Avogadro constant $=6.023 \times 10^{23} \mathrm{~mol}^{-1}$ ) [Main Online April 16, 2018]
(a) $6.023 \times 10^{9}$
(b) $6.023 \times 10^{23}$
(c) $6.023 \times 10^{21}$
(d) $6.023 \times 10^{20}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:41

Problem 8

The most abundant elements by mass in the body of a healthy human adult are :
[Main 2017] Oxygen $(61.4 \%)$; Carbon $(22.9 \%)$, Hydrogen $(10.0 \%)$; and Nitrogen $(2.6 \%)$. The weight which a $75 \mathrm{~kg}$ person would gain if all ${ }^{1} \mathrm{H}$ atoms are replaced by ${ }^{2} \mathrm{H}$ atoms is
(a) $15 \mathrm{~kg}$
(b) $37.5 \mathrm{~kg}$
(c) $7.5 \mathrm{~kg}$
(d) $10 \mathrm{~kg}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:55

Problem 9

What quantity (in mL) of a $45 \%$ acid solution of a mono-protic strong acid must be mixed with a $20 \%$ solution of the same acid to produce $800 \mathrm{~mL}$ of a $29.875 \%$ acid solution? [Main Online April 9, 2017]
(a) 320
(b) 325
(c) 316
(d) 330

Akhil Choudhary
Akhil Choudhary
Numerade Educator
03:35

Problem 10

At $300 \mathrm{~K}$ and $1 \mathrm{~atm}, 15 \mathrm{~mL}$ of a gaseous hydrocarbon requires 375 $\mathrm{mL}$ air containing $20 \% \mathrm{O}_{2}$ by volume for complete combustion. Aftercombustion the gases occupy $330 \mathrm{~mL}$. Assuming that the water formed is in liquid form and the volumes were measured at the same temperature and pressure, the formula of the hydrocarbon is:
[Main 2016]
(a) $\mathrm{C}_{4} \mathrm{H}_{8}$
(b) $\mathrm{C}_{4} \mathrm{H}_{10}$
(c) $\mathrm{C}_{3} \mathrm{H}_{6}$
(d) $\mathrm{C}_{3} \mathrm{H}_{8}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:12

Problem 11

$5 \mathrm{~L}$ of an alkane requires $25 \mathrm{~L}$ of oxygen for its complete combustion. If all volumes are measured at constant temperature and pressure, the alkane is:
[Main Online April 9, 2016]
(a) Isobutane
(b) Ethane
(c) Butane
(d) Propane

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:51

Problem 12

The molecular formula of a commercial resin used for exchanging ions in water softening is $\mathrm{C}_{8} \mathrm{H}_{7} \mathrm{SO}_{3}^{-} \mathrm{Na}^{+}$(Mol. wt. 206. What would be the maximum uptake of $\mathrm{Ca}^{2+}$ ions by the resin when expressed in mole per gram resin? [Main 2015]
(a) $\frac{2}{309}$
(b) $\frac{1}{412}$
(c) $\frac{1}{103}$
(d) $\frac{1}{206}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:32

Problem 13

Choose the incorrect formula out of the four compounds for an element X below :[Main Online April 11, 2015]
(a) $\mathrm{X}_{2} \mathrm{O}_{3}$
(b) $\mathrm{X}_{2} \mathrm{Cl}_{3}$
(c) $\mathrm{X}_{2}\left(\mathrm{SO}_{4}\right)_{3}(\mathrm{~d}) \mathrm{XPO}_{4}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:41

Problem 14

Dissolving $120 \mathrm{~g}$ of a compound of (mol. wt. 60) in $1000 \mathrm{~g}$ of water gave a solution of density $1.12 \mathrm{~g} / \mathrm{mL}$. The molarity of the solution is:(a) $1.00 \mathrm{M}$
(b) $2.00 \mathrm{M}$
(c) $2.50 \mathrm{M}$
(d) $4.00 \mathrm{M}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:48

Problem 15

A gaseous hydrocarbon gives upon combustion $0.72 \mathrm{~g}$ of water and $3.08 \mathrm{~g}$. of $\mathrm{CO}_{2}$. The empirical formula of the hydrocarbon is:
[Main 2013]
(a) $\mathrm{C}_{2} \mathrm{H}_{4}$
(b) $\mathrm{C}_{3} \mathrm{H}_{4}$
(c) $\mathrm{C}_{6} \mathrm{H}_{5}$
(d) $\mathrm{C}_{7} \mathrm{H}_{8}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:24

Problem 16

$10 \mathrm{~mL}$ of $2(\mathrm{M}) \mathrm{NaOH}$ solution is added to $200 \mathrm{~mL}$ of $0.5(\mathrm{M})$ of $\mathrm{NaOH}$ solution. What is the final concentration? [Main Online April 25, 2013]
(a) $0.57(\mathrm{M})$
(b) $5.7(\mathrm{M})$
(c) $11.4(\mathrm{M})$
(d) $1.14(\mathrm{M})$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:51

Problem 17

The density of $3 \mathrm{M}$ solution of sodium chloride is $1.252 \mathrm{~g} \mathrm{~mL}^{-1}$. The molality of the solution will be :
(molar mass, $\left.\mathrm{NaCl}=58.5 \mathrm{~g} \mathrm{~mol}^{-1}\right)$
[Main Online April 22, 2013]
(a) $260 \mathrm{~m}$
(b) $2.18 \mathrm{~m}$
(c) $2.79 \mathrm{~m}$
(d) $3.00 \mathrm{~m}$
Page $23 \quad / 1,773$
$\mathbb{Q}+$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:56

Problem 18

Which has maximum number of atoms? [2003S]
(a) $24 \mathrm{~g}$ of $\mathrm{C}(12)$
(b) $56 \mathrm{~g}$ of $\mathrm{Fe}(56)$
(c) $27 \mathrm{~g}$ of $\mathrm{Al}(27)$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:19

Problem 19

How many moles of electron weigh one kilogram?
(a) $\frac{1}{206}$
(b) $\frac{1}{9.108} \times 10^{31}$
(c) $\frac{6.023}{9.108} \times 10^{54}$
(d) $\frac{1}{9.108 \times 6.023} \times 10^{8}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
00:47

Problem 20

If two compounds have the same empirical formula but different molecular fomulae they must have [1987-1 Mark]
(a) different percentage composition
(b) different molecular weight
(c) same viscosity
(d) same vapour density

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:06

Problem 21

The largest number of molecules is in $[1979]$
(a) $36 \mathrm{~g}$ of water
(b) $28 \mathrm{~g}$ of carbon monoxide
(c) $46 \mathrm{~g}$ of ethyl alcohol
(d) $54 \mathrm{~g}$ of nitrogen pentoxide

Akhil Choudhary
Akhil Choudhary
Numerade Educator
00:53

Problem 22

The total number of electrons in one molecule of carbon dioxide is [1979]
(a) 22
(b) 44
(c) 66
(d) 88

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:34

Problem 23

A gaseous mixture contains oxygen and nitrogen in the ratio of $1: 4$ by weight. Therefore, the ratio of their number of molecules is [1979]
(a) $1: 4$
(b) $1: 8$
(c) $7: 32$
(d) $3: 16$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:34

Problem 24

$27 \mathrm{~g}$ of $\mathrm{Al}$ will react completely with how many grams of oxygen? [1978]
(a) $8 \mathrm{~g}$
(b) $16 \mathrm{~g}$
(c) $32 \mathrm{~g}$
(d) $24 \mathrm{~g}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:17

Problem 25

A compound was found to contain nitrogen and oxygen in the ratio 28 $\mathrm{g}$ and $80 \mathrm{~g}$ respectively. The formula of compound is [1978]
(a) $\mathrm{NO}$
(b) $\mathrm{N}_{2} \mathrm{O}_{3}$
(c) $\mathrm{N}_{2} \mathrm{O}_{5}$
(d) $\mathrm{N}_{2} \mathrm{O}_{4}$

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:18

Problem 26

The ratio of the mass percentages of ' $\mathrm{C} \& \mathrm{H}$ ' and ' $\mathrm{C}$ \& $\mathrm{O}$ ' of a saturated acyclic organic compound ' $\mathrm{X}$ ' are $4: 1$ and $3: 4$ respectively. Then, the moles of oxygen gas required for complete combustion of two moles of organic compound ' $\mathrm{X}$ ' is [Main Sep. 02, 2020 (II)]

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:58

Problem 27

The molarity of $\mathrm{HNO}_{3}$ in a sample which has density $1.4 \mathrm{~g} / \mathrm{mL}$ and mass percentage of $63 \%$ is . (Molecular Weight of $\mathrm{HNO}_{3}=$
63) [Main Jan. 09, 2020 (I)]

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:41

Problem 28

If the value of Avogadro number is $6.023 \times 10^{23} \mathrm{~mol}^{-1}$ and the value of Boltzmann constant is $1.380 \times 10^{-23} \mathrm{~J} \mathrm{~K}^{-1}$, then the number of significant digits in the calculated value of the universal gas constant is [Adv. 2014]

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:02

Problem 29

Calculate the molarity of water if its density is $1000 \mathrm{~kg} / \mathrm{m}^{3}$. [2003 - 2 Marks]

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:05

Problem 30

The composition of a sample of Wurtzite is $\mathrm{Fe}_{0.93} \mathrm{O}_{1.00}$. What percentage of the iron is present in the form of Fe (III)? [1994-2 Marks]

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:42

Problem 31

A compound contains 28 percent of nitrogen and 72 percent of metal by weight. 3 atoms of metal combine with 2 atoms of $\mathrm{N}$. Find the atomic weight of metal.

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:32

Problem 32

The weight of $1 \times 10^{22}$ molecules of $\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}$ is $\ldots \ldots \ldots \ldots \ldots .$
[1991 - 1 Mark]

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:03

Problem 33

The modern atomic mass unit is based on ........................ [1980]

Akhil Choudhary
Akhil Choudhary
Numerade Educator
01:19

Problem 34

The total number of electrons present in $18 \mathrm{~mL}$ of water is ...........................
[1980]

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:18

Problem 35

A plant virus is found to consist of uniform cylindrical particles of $150 \AA$ in diameter and $5000 \AA$ long. The specific volume of the virus is $0.75 \mathrm{~cm}^{3} / \mathrm{g}$. If the virus is considered to be a single particle, find its molar mass.

Akhil Choudhary
Akhil Choudhary
Numerade Educator
11:04

Problem 36

(a) One litre of a sample of hard water contains $1 \mathrm{mg}$ of $\mathrm{CaCl}_{2}$ and 1 $\mathrm{mg}$ of $\mathrm{MgCl}_{2}$. Find the total hardness in terms of parts of $\mathrm{CaCO}_{3}$ per $10^{6}$ parts of water by weight.
(b) A sample of hard water contains $20 \mathrm{mg}$ of $\mathrm{Ca}^{++}$ions per litre. How many milli-equivalent of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ would be required to soften 1 litre of the sample?
(c) $1 \mathrm{~g}$ of $\mathrm{Mg}$ is burnt in a closed vessel which contains $0.5 \mathrm{~g}$ of $\mathrm{O}_{2}$.
(i) Which reactant is left in excess?
(ii) Find the weight of the excess reactants?
(iii) How may milliliters of $0.5 \mathrm{~N} \mathrm{H}_{2} \mathrm{SO}_{4}$ will dissolve the residue in the vessel.

Sriparna Bhattacharjee
Sriparna Bhattacharjee
Numerade Educator
02:05

Problem 37

A hydrocarbon contains $10.5 \mathrm{~g}$ of carbon per gram of hydrogen. 1 litre of the vapour of the hydrocarbon at $127^{\circ} \mathrm{C}$ and 1 atmosphere pressure weighs $2.8 \mathrm{~g}$. Find the molecular formula.

Akhil Choudhary
Akhil Choudhary
Numerade Educator
02:21

Problem 38

Find
(i) The total number of neutrons and
(ii) The total mass of neutron in $7 \mathrm{mg}$ of ${ }^{14} \mathrm{C}$. (Assume that mass of neutron = mass of hydrogen atom)

Akhil Choudhary
Akhil Choudhary
Numerade Educator