Problems in Physical Chemistry for JEE

Narendra Avasthi

Chapter 2

Atomic Structure - all with Video Answers

Educators

Chapter Questions

Problem 1

Which of the following pair is isodiaphers?
(a) ${ }_{6}^{14} \mathrm{C}$ and ${ }_{11}^{23} \mathrm{Na}$
(b) $_{12}^{24} \mathrm{Mg}$ and ${ }_{11}^{23} \mathrm{Na}$
(c) ${ }_{2}^{4} \mathrm{He}$ and ${ }_{8}^{16} \mathrm{O}$.
(d) ${ }_{6}^{12} \mathrm{C}$ and ${ }_{7}^{15} \mathrm{~N}$

Ajay Singhal

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Problem 2

Which of the following does not characterise X-rays?
(a) The radiation can ionise the gas
(b) It causes fluorescence effect on $\mathrm{ZnS}$
(c) Deflectéd by electric and magnetic fields
(d) Have wavelength shorter than ultraviolet rays

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Problem 3

The ratio of specific charge óf a proton and an $\alpha$ -particle is
(a) $2: 1$
(b) $1: 2$
(c) $1: 4$
(d) $1: 1$

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Problem 4

The increasing order for the values of $e / m$ (charge/mass) is :
(a) $e, p, n, \alpha$
(b) $n, p, e, \alpha$
(c) $n, p, \alpha, e$
(d) $n, \alpha, p, e$

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Problem 5

The mass to charge ratio $(m / e)$ for a cation is $1.5 \times 10^{-8} \mathrm{~kg} / \mathrm{C}$. What is the mass of this atom?
(a) $2.4 \times 10^{-19} \mathrm{~g}$
(b) $2.4 \times 10^{-27} \mathrm{~g}$
(c) $2.4 \times 10^{-24} \mathrm{~g}$
(d) None of these.

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Problem 6

Rutherford's experiment on scattering of alpha particles showed for the first time that atom has:
(a) Electrons
(b) Protoris
(c) Nucleus
(d) Neutrons

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Problem 7

a-particles are represented by
(a) Lithium atoms
(b) Helium nuclei
(c) Hydrogen nuclei
(d) None of these

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Problem 8

In Bohr's stationary orbits
(a) Electrons do not move
(b) Electrons move emitting radiations
(c) Energy of the electron remains constant
(d) Angular momentum of the electron is $h / 2 \pi$

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Problem 9

On the basis of Bohr's model, the radius of the 3rd orbit is
(a) Equal to the radius of first orbit
(b) Three times the radius of first orbit
(c) Five times the radius of first orbit
(d) Nine times the radius of first orbit

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Problem 10

The correct expression derived for the energy of an electron in the $n^{\text {th }}$ energy level is for H-atom
(a) $E_{n}=\frac{2 \pi^{2} m e^{4}}{n^{2} h^{2}}$
(b) $E_{n}=-\frac{\pi^{2} m e^{4}}{2 n^{2} h^{2}}$
(c) $E_{n}=-\frac{2 \pi^{2} m e^{2}}{n^{2} h^{2}}$
(d) $E_{n}=-\frac{2 \pi^{2} m e^{4}}{n^{2} h^{2}}$

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Problem 11

Ionization energy for hydrogen atom in ergs, Joules and $\mathrm{eV}$ respectively is $\therefore$
(a) $21.8 \times 10^{-12}, 218 \times 10^{-20}, 136$
(b) $13.6 \times 218 \times 10^{-20}, 21.8 \times 10^{-13}$
(c) $21.8 \times 10^{-20}, 13.6,218 \times 10^{-13}$
(d) $21.8 \times 10^{-13}, 13.6,21.8 \times 10^{-20}$

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Problem 12

For any $\mathrm{H}$ like system, the ratio of velocities of $\mathrm{I}$, II $\&$ III orbit $i . e ., V_{1}: V_{2}: V_{3}$ will be
(a) $1: 2: 3$
(b) $1: 1 / 2: 1 / 3$
(c) $3: 2: 1$
(d) $1: 1: 1$

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Problem 13

The volume of nucleus is about:
(a) $10^{-4}$ times to that of an atom
(b) $10^{-15}$ times to that of an atom
(c) $10^{-5}$ times to that of an atom
(d) $10^{-10}$ times to that of an atom

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Problem 14

An electron in an atom jumps in such a way that its kinetic energy changes from $x$ to $\frac{x}{4}$. The change in potential energy will be :
(a) $+\frac{3}{2} x$
(b) $-\frac{3}{8} x$
(c) $+\frac{3}{4} x$
(d) $-\frac{3}{4} x$

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Problem 15

The potential energy of an electron in the hydrogen atom is $-6.8 \mathrm{eV}$. Indicate in which excited state, the electron is present?
(a) first
(b) second
(c) third
(d) fourth

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Problem 16

What is the potential energy of an electron present in $N$ -shell of the $\mathrm{Be}^{3+}$ ion?
(a) $-3.4 \mathrm{eV}$
(b) $-6.8 \mathrm{eV}$
(c) $-13.6 \mathrm{eV}$
(d) $-27.2 \mathrm{eV}$

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Problem 17

The kinetic and potential energy (in $\mathrm{eV}$ ) of electron present in third Bohr's orbit of hydrogen atom are respectively :
(a) $-1.51,-3.02$
(b) $1.51,-3.02$
(c) $-3.02,1.51$
(d) $1.51,-1.51$

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Problem 18

The distance between 4 th and 3 rd Bohr orbits of $\mathrm{He}^{+}$ is :
(a) $2.645 \times 10^{-10} \mathrm{~m}$
(b) $1.322 \times 10^{-10} \mathrm{~m}$
(c) $1.851 \times 10^{-10} \mathrm{~m}$
(d) None

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Problem 19

What atomic number of an element " $X$ " would have to become so that the 4 th orbit around $X$ would fit inside the 1st Bohr orbit of $\mathrm{H}$ atom ?
(a) 3
(b) 4
(c) 16
(d) 25

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Problem 20

The ratio of velocity of the electron in the third and fifth orbit of $\mathrm{Li}^{2+}$ would be :
(a) $3: 5$
(b) $5: 3$
(c) $25: 9$
(d) $9 \because 25$

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Problem 21

If radius of second stationary orbit (in Bohr's atom) is $R$. Then radius of third orbit will be :
(a) $R / 3$
(b) $9 R$
(c) $R / 9$
(d) $2.25 \mathrm{R}$

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Problem 22

Which state of $\mathrm{Be}^{3+}$ has the same orbit radius as that of the ground state of hydrogen atom?
(a) 3
(b) 2
(c) 4
(d) 5

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Problem 23

Select the incorrect graph for velocity of $e^{-}$ in an orbit vs. $Z, \frac{1}{n}$ and $n:$

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Problem 24

What is the frequency of revolution of electron present in 2 nd Bohr's orbit of $H$ -atom?
(a) $1.016 \times 10^{16} \mathrm{~s}^{-1}$
(b) $4.065 \times 10^{16} \mathrm{~s}^{-1}$
(c) $1.626 \times 10^{15} \cdot \mathrm{s}^{-1}$
(d) $8.2 \times 10^{14} \mathrm{~s}^{-1}$

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Problem 25

An electron travels with a velocity of $x \mathrm{~ms}^{-1}$. For a proton to have the same de-Broglie wavelength, the velocity will be approximately:
(a) $\frac{1840}{x}$
(b) $\frac{x}{1840}$
(c) $1840 x$
(d) $x$

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Problem 26

According to Bohr's atomic theory, which of the following is correct ?
(a) Potential energy of electron $\propto \frac{Z^{2}}{n^{2}}$
(b) The product of velocity of electron and principle quantum number $(n) \propto Z^{2}$
(c) Frequency of revolution of electron in an orbit $\propto \frac{Z^{2}}{n^{3}}$
(d) Coulombic force of attraction on the electron $\propto \frac{Z^{2}}{n^{2}}$

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Problem 27

Number of waves produced by an electron in one complete revolution in $n^{\text {un }}$ orbit is :
(a) $n$
(b) $n^{2}$
(c) $(n+1)$
(d) $(2 n+1)$

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Problem 28

Electronic transition in $\mathrm{He}^{+}$ ion takes from $n_{2}$ to $n_{1}$ shell such that :
$2 n_{2}+3 n_{1}=18$
$2 n_{2}-3 n_{1}=6$
$+$
What will be the total number of photons emitted when electrons transit to $n_{1}$ shell?
(a) 21
(b) 15
(c) 20
(d) 10

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Problem 29

Which of the following expressions represents the spectrum of Balmer series (If $\mathrm{n}$ is the ' principal quantum number of higher energy level) in Hydrogen atom ?
(a) $\bar{v}=\frac{R(n-1)(n+1)}{n^{2}} \mathrm{~cm}^{-1}$
(b) $\bar{v}=\frac{R(n-2)(n+2)}{4 n^{2}} \mathrm{~cm}^{-1}$
(c) $\bar{v}=\frac{R(n-2)(n+2)}{n^{2}} \mathrm{~cm}^{-1}$
(d) $\bar{v}=\frac{R(n-1)(n+1)}{4 n^{2}} \mathrm{~cm}^{-1}$

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Problem 30

Multiple of fine structure of spectral lines is due to
(a) Presence of main energy levels
(b) Presence of sub-levels
(c) Presence of electronic configuration
(d) Is not a characteristics of the atom

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Problem 31

Which of the following statement does not form part of Bohr's model of the hydrogen atom ?
(a) Energy of the electrons in the orbit is quantized
(b) The electron in the orbit nearest the nucleus has the lowest energy
(c) Electrons revolve in different orbits around the nucleus
(d) The position and velocity of the electrons in the orbit cannot be determined simultaneously

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Problem 32

With increasing principle quantum number, the energy difference between adjacent energy levels in $\mathrm{H}$ -atom:
(a) decreases
(b) increases
(c) remains constant
(d) decreases for low value of $Z$ and increases for higher value of $Z$.

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Problem 33

What is the separation energy (in $\mathrm{eV}$ ) for $\mathrm{Be}^{3+}$ in the first excited state in $\mathrm{eV}$ ?
(a) $13.6 \mathrm{eV}$
(b) $27.2 \mathrm{eV}$
(c) $40.8 \mathrm{eV}$
(d) $54.5 \mathrm{eV}$

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Problem 34

If in Bohr's model, for unielectronic atom, time period of revolution is represented as $T_{n, Z}$ where $n$ represents shell no. and $Z$ represents atomic number then the value of $T_{1,2}: T_{2,1}$ will
be :
(a) $8: 1$
(b) $1: 8$
(c) $1: 1$
(d) $1: 32$

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Problem 35

Which of the following is discreted in Bohr's theory?
(a) Potential energy
(b) Kinetic energy
(c) Velocity
(d) Angular momentum

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Problem 36

What is the ratio of time periods $\left(T_{1} / T_{2}\right)$ in second orbit of hydrogen atom to third orbit of $\mathrm{He}^{+}$ ion?
(a) $8 / 27$
(b) $32 / 27$
(c) $27 / 32$
(d) None of these

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Problem 37

$\mathrm{Be}^{3+}$ and a proton are accelerated by the same potential, their de-Broglie wavelengths have the ratio (assume mass of proton = mass of neutron):
(a) $1: 2$
(b) $1: 4$
(c) $1: 1$
(d) $1: 3 \sqrt{3}$

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Problem 38

The mass of an electron is $m$, charge is $e$ and it is accelerated from rest through a potential difference of $V$ volts. The velocity acquired by electron will be :
(a) $\sqrt{\frac{V}{m}}$
(b) $\sqrt{\frac{e V}{m}}$
(c) $\sqrt{\frac{2 e V}{m}}$
(d) zero

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Problem 39

The spectrum produced from an element is :
(a) atomic spectrum
(b) line spectrum
(c) absorption spectrum
(d) any one of the above

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Problem 40

Line spectra is characteristic of :
(a) molecules
(b) atoms
(c) radicals
(d) none of these

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Problem 41

If the ionization energy of $\mathrm{He}^{+}$ is $19.6 \times 10^{-18} \mathrm{~J}$ per atom then the energy of $\mathrm{Be}^{3+}$ ion in the second stationary state is $\begin{array}{llll}\text { (a) }-4.9 \times 10^{-18} \mathrm{~J} & \text { (b) }-44.1 \times 10^{-18} \mathrm{~J} & \text { (c) }-11.025 \times 10^{-18} \mathrm{~J} \text { (d) None of these }\end{array}$

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Problem 42

Find the value of wave number $(\bar{v})$ in terms of Rydberg's constant, when transition of electron takes place between two levels of $\mathrm{He}^{+}$ ion whose sum is 4 and difference is $2 .$
(a) $\frac{8 R}{9}$
(b) $\frac{32 R}{9}$
(c) $\frac{3 R}{4}$
(d) none of these

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Problem 43

A $\mathrm{H}$ -atom moving at a speed $(v)$ absorbs a photon of $\lambda=122 \mathrm{~nm}$ and stops. What was the speed of $\mathrm{H}$ -atom? $\left(h=6.63 \times 10^{-34} \mathrm{~J}-\mathrm{s}\right)$
(a) $0.325 \mathrm{~m} / \mathrm{s}$
(b) $1 \mathrm{~m} / \mathrm{s}$
(c) $2.5 \mathrm{~m} / \mathrm{s}$
(d) $3.25 \mathrm{~m} / \mathrm{s}$

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Problem 44

Assume that $2 \times 10^{-17} \mathrm{~J}$ of light energy is needed by the interior of the human eye to see an object. How many photons of yellow light with $\lambda=595.2 \mathrm{~nm}$ are needed to generate this minimum energy?
(a) 6
(b) 30
(c) 45
(d) 60

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Problem 45

Which graph shows how the energy $E$ of a photon of light is related to its wavelengths $(l) ?$

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Problem 46

The mass of a particle is $10^{-10} \mathrm{~g}$ and its radius is $2 \times 10^{-4} \mathrm{~cm}$. If its velocity is $10^{-6} \mathrm{~cm} \mathrm{sec}^{-1}$ with $0.0001 \%$ uncertainty in measurement, the uncertainty in its position is :
(a) $5.2 \times 10^{-8} \mathrm{~m}$
(b) $5.2 \times 10^{-7} \cdot \mathrm{m}$
(c) $5.2 \times 10^{-6} \mathrm{~m}$
(d) $5.2 \times 10^{-9}$

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Problem 47

If an electron is travelling at $200 \mathrm{~m} / \mathrm{s}$ within $1 \mathrm{~m} / \mathrm{s}$ uncertainty, what is the theoretical uncertainty in its position in $\mu \mathrm{m}$ (micrometer)?
(a) $14.5$
(b) 29
(c) 58
(d) 114

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Problem 48

The energy of the second Bohr orbit in the hydrogen atom is $-3.41 \mathrm{eV}$. The energy of the second Bohr orbit of $\mathrm{He}^{+}$ ion would be :
(a) $-0.85 \mathrm{eV}$
(b) $-13.64 \mathrm{eV}$
(c) $-1.70 \mathrm{eV}$
(d) $-6.82 \mathrm{eV}$

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Problem 49

Which of the following statement(s) is/are consistent with the Bohr theory of the atom (and no others)?
(1) An electron can remain in a particular orbit as long as it continuously absorbs radiation of a definite frequency.
(2) The lowest energy orbits are those closest to the nucleus.
(3) All electrons can jump from the $K$ shell to the $M$ shell by emitting radiation of a definite frequency.
(a) $1,2,3$
(b) 2 only
(c) 3 only
(d) 1,2

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Problem 50

Wavelength for high energy EMR transition in H-atom is $91 \mathrm{~nm}$. What energy is needed for this transition?
(a) $1.36 \mathrm{eV}$
(b) $1240 \mathrm{eV}$
(c) $13 \mathrm{eV}$
(d) $13.6 \mathrm{eV}$

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Problem 51

The ionization potential for the electron in the ground state of the hydrogen atom is $13.6 \mathrm{eV}$ atom $^{-1}$. What would be the ionization potential for the electron in the first excited state of $\mathrm{Li}^{2+}$ ?
(a) $3.4 \mathrm{eV}$
(b) $10.2 \mathrm{eV}$
(c) $30.6 \mathrm{eV}$
(d) $6.8 \mathrm{eV}$

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Problem 52

What is the energy content per photon $(J)$ for light of frequency $4.2 \times 10^{14}$ ?
(a) $2.8 \times 10^{-21}$
(b) $2.5 \times 10^{-19}$
(c) $2.8 \times 10^{-19}$
(d) $2.5 \times 10^{-18}$

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Problem 53

What is the wavelength in $\mathrm{nm}$ of the spectral line associated with a transition from $n=3$ to $n=2$ for the $\mathrm{Li}^{2+}$ ion?
(a) 219
(b) 656
(c) $73.0$.
(d) 486

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Problem 54

What is the energy $(\mathrm{kJ} / \mathrm{mol})$ associated with the de-excitation of an electron from $n=6$ tó $n=2$ in $\mathrm{He}^{+}$ ion?
(a) $1.36 \times 10^{6}$
(b) $1.36 \times 10^{3}$
(c) $1.16 \times 10^{3}$
(d) $1.78 \times 10^{3}$

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Problem 55

The momentum (in $\mathrm{kg}-\mathrm{m} / \mathrm{s}$ ) of photon having $6 \mathrm{MeV}$ energy is :
(a) $3.2 \times 10^{-21}$
(b), $2.0$
(c) $1.6 \times 10^{-21}$
(d) none of these

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Problem 56

The H-spectrum show:
(a) Heisenberg's uncertainty principle
(b) Diffraction
(c) Polarization
(d) Presence of quantized energy level

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Problem 57

The energy of an electron moving in $n^{\text {th }}$ Bohr's orbit of an element is given by $E_{n}=\frac{-13.6}{n^{2}} Z^{2}$ $\mathrm{eV} /$ atom $(Z=$ atomic number $)$. The graph of $E$ vs. $Z^{2}$ (keeping "n" constant) will be :

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Problem 58

If $\varepsilon_{0}$ be the permittivity of vacuum and $r$ be the radius of orbit of $\mathrm{H}$ -atom in which electron is revolving then velocity of electron is given by :
(a) $v=\frac{e}{\sqrt{4 \pi \varepsilon_{0} r m}}$
(b) $v=e \times \sqrt{4 \pi \varepsilon_{0} r m}$
(c) $v=\frac{4 \pi \varepsilon_{0} r m}{e}$
(d) $v=\frac{4 \pi \varepsilon_{0} r m}{e^{2}}$

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Problem 59

What is the shortest wavelength line in the Paschen series of $\mathrm{Li}^{2+}$ ion?
(a) $\frac{R}{9}$
(b) $\frac{9}{R}$
(c) $\frac{1}{R}$
(d) $\frac{9 R}{4}$

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Problem 60

What is the maximum wavelength line in the Lyman series of $\mathrm{He}^{+}$ ion?
(a) $3 R$
(b) $\frac{1}{3 R}$
(c) $\frac{4}{4 R}$
(d) None of these

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Problem 61

Splitting of spectral lines under the influence of magnetic field is called
(a) Zeeman effect
(b) Stark effect
(c) Photoelectric effect
(d) None of these

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Problem 62

The colour of sky is due to lis
(a) Absorption of light by atmospheric gases
(b) Transmission of light
(c) Wavelength of scattered light
(d) All- of the above

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Problem 63

In photoelectric effect, the kinetic energy of photoelectrons increases linearly with the
(a) Wavelength of incident light
(b) Frequency of incident light
(c) Velocity of incident light
(d) Atomic mass of an element

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Problem 64

Slope of $V_{0}$ vs $v$ curve is (where $V_{0}=$ Stopping potential, $v=$ subjected frequency)
(a) $e$
(b) $\frac{h}{-}$
(c) $\phi$
(d) $h$

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Problem 65

According to Einstein's photoelectric equation, the graph between kinetic energy of photoelectrons ejected and the frequency of the incident radiation is :

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Problem 66

The photoelectric emission from a surface starts only when the light incident upon the surface has certain minimum :
(a) intensity
(b) wavelength
(c) frequency
(d) velocity

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Problem 67

If $\lambda_{0}$ and $\lambda$ be the threshold wavelength and the wavelength of incident light, the velocity of photo-electrons ejected from the metal surface is :
(a) $\sqrt{\frac{2 h}{m}\left(\lambda_{0}-\lambda\right)}$
(b) $\sqrt{\frac{2 h c}{m}\left(\lambda_{0}-\lambda\right)}$
(c) $\sqrt{\frac{2 h c}{m}\left(\frac{\lambda_{0}-\lambda}{\lambda \lambda_{0}}\right)}$
(d) $\sqrt{\frac{2 h}{m}\left(\frac{1}{\lambda_{0}}-\frac{1}{\lambda}\right)}$

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Problem 68

A light source of wavelength $\lambda$ illuminates a metal and ejects photo-electrons with $\left(\mathrm{K} . \mathrm{E}_{t}\right)_{\max }=1 \mathrm{eV}$
Another light source of wavelength $\frac{\lambda}{3}$, ejects photo-electrons from same metal with (K. E.) $_{\max }=4 \mathrm{eV}$
Find the value of work function?
(a) $1 \mathrm{eV}$
(b) $2 \mathrm{eV}$
(c) $0.5 \mathrm{eV}$
(d) None of these

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Problem 69

Electromagnetic radiation having $\lambda=310 \AA$ is subjected to a metal sheet having work function $=12.8 \mathrm{eV}$. What will be the velocity of photo-electrons having maximum kinetic energy.
(a) 0, no emission will occur
(b) $4.352 \times 10^{6} \mathrm{~m} / \mathrm{s}$
(c) $3.09 \times 10^{6} \mathrm{~m} / \mathrm{s}$
(d) $8.72 \times 10^{6} \mathrm{~m} / \mathrm{s}$

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Problem 70

The ratio of slopes of $K_{\max }$ vs. $v$ and $V_{0}$ vs. $v$ curves in the photoelectric effect gives $(v=$ frequency, $K_{\max }=$ maximum kinetic energy, $V_{0}=$ stopping potential):
(a) charge of electron
(b) Planck's constant
(c) work function
(d) the ratio of Planck's constant of electronic charge

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Problem 71

Radiation corresponding to the transition $n=4$ to $n=2$ in hydrogen atoms falls on a certain metal (work function $=2.5 \mathrm{eV}$ ). The maximum kinetic energy of the photo-electrons will be:
(a) $0.55 \mathrm{eV}$
(b) $2.55 \mathrm{eV}$
(c) $4.45 \mathrm{eV}$
(d) None of these

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Problem 72

Select the incorrect statement:
(a) K.E. of photo-electron does not depend upon the wavelength of incident radiation
(b) Photoelectric current depends on intensity of incident radiation and not on frequency
(c) Stopping potential depends on frequency of radiation and not on intensity
(d) None of these

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Problem 73

The de-Broglie wavelength of an electron accelerated by an electric field of $V$ volts is given by:
(a) $\lambda=\frac{1.23}{\sqrt{m}}$
(b) $\lambda=\frac{1.23}{\sqrt{h}} m$
(c) $\lambda=\frac{1.23}{\sqrt{V}} \mathrm{~nm}$
(d) $\lambda=\frac{1.23}{V}$

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Problem 74

Which is the de-Broglie equation:
(a) $h=p \lambda$
(b) $h=p \lambda^{-1}$
(c) $h=\lambda p^{-1}$
(d) $h=p+\lambda$

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Problem 75

Which of the following has the largest de Broglie wavelength (all have equal velocity)
(a) $\mathrm{CO}_{2}$ molecule
(b) $\mathrm{NH}_{3}$ molecule
(c) Electron
(d) Proton

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Problem 76

$\sqrt{V}$ on two particles $A$ and $B$ are plotted against de-Broglie wavelengths. Where $V$ is the potential on the particles. Which of the following relation is correct about the mass of particles?

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Problem 77

Which of following graphs correctly represents the variation of particles momentum with de-Broglie wavelength ?

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Problem 78

An excited state of $\mathrm{H}$ atom emits a photon of wavelength $\lambda$ and returns in the ground state, the principal quantum number of excited state is given by :
(a) $\sqrt{\lambda R(\lambda R-1)}$
(b) $\sqrt{\frac{\lambda R}{(\lambda R-1)}}$
(c) $\sqrt{\lambda R(\lambda R-1)}$
(d) $\sqrt{\frac{(\lambda R-1)}{\lambda R}}$
39

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Problem 79

A dye absorbs a photon of wavelength $\lambda$ and re-emits the same energy into two photons of wavelengths $\lambda_{1}$ and $\lambda_{2}$ respectively. The wavelength $\lambda$ is related with $\lambda_{1}$ and $\lambda_{2}$ as :
(a) $\lambda=\frac{\lambda_{1}+\lambda_{2}}{\lambda_{1} \lambda_{2}}$
(b) $\lambda=\frac{\lambda_{1} \lambda_{2}}{\lambda_{1}+\lambda_{2}}$
(c) $\lambda=\frac{\lambda_{1}^{2} \lambda_{2}^{2}}{\lambda_{1}+\lambda_{2}}$
(d) $\lambda=\frac{\lambda_{1} \lambda_{2}}{\left(\lambda_{1}+\lambda_{2}\right)^{2}}$

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Problem 80

Which of the following electron transitions in a hydrogen atom will require the largest amount of energy?
(a) from $n=1$ to $n=2$
(b) from $n=2$ to $n=4$
(c) from $n=5$ to $n=1$
(d) from $n=3$ to $n=5$

Ajay Singhal

Numerade Educator

Problem 81

If $a_{0}$ be the radius of first Bohr's orbit of $\mathrm{H}$ -atom, the de-Broglie's wavelength of an electron revolving in the second Bohr's orbit will be :
(a) $6 \pi a_{0}$
(b) $4 \pi a_{0}$
(c) $2 \pi a_{0}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 82

Which electronic transition in a hydrogen atom, starting from the orbit $n=7$, will produce infrared light of wavelength $2170 \mathrm{~nm}$ ? (Given : $R_{H}=1.09677 \times 10^{7} \mathrm{~m}^{-1}$ )
(a) $n=7$ to $n=6$
(b) $n=7$ to $n=5$
(c) $n=7$ to $n=4$
(d) $n=7$ to $n=3$

Ajay Singhal

Numerade Educator

Problem 83

A hydrogen atom in the ground state is excited by monochromatic radiation of wavelength $\lambda \AA .$ The resulting spectrum consists of maximum 15 different lines. What is the wavelength $\lambda ?$ $\left(R_{H}=109737 \mathrm{~cm}^{-1}\right)$
(a) $937.3 \AA$
(b) $1025 \AA$
(c) $1236 \AA$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 84

In any subshell, the maximum number of electrons having same value of spin quantum number is :
(a) $\sqrt{l(l+1)}$
(b) $l+2$
(c) $2 l+1$
(d) $4 l+2$

Ajay Singhal

Numerade Educator

Problem 85

The number of photons of light having wave number ' $x$ ' in $10 \mathrm{~J}$ of energy source is :
(a) $10 h c x$
(b) $\frac{h c}{10 x}$
(c) $\frac{10}{h c x}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 86

Which of the following relates to photons both as wave motion and as a stream of particles?
(a) Interference
(b) $E=m c^{2}$
(c) Diffraction
(d) $E=h v$

Ajay Singhal

Numerade Educator

Problem 87

Electromagnetic radiation (photon) with highest wavelength results when an electron in the hydrogen atom falls from $n=6$ to :
(a) $n=1$
(b) $n=2$
(c) $n=3$
(d) $n=5$

Ajay Singhal

Numerade Educator

Problem 88

Energy required to ionise 2 mole of gaseous $\mathrm{He}^{+}$ ion present in its ground state is :
(a) $54.4 \mathrm{eV}$
(b) $108.8 \mathrm{~N}_{A} \mathrm{eV}$
(c) $54.4 \mathrm{~N}_{A} \mathrm{eV}$
(d) $108.8 \mathrm{eV}$

Ajay Singhal

Numerade Educator

Problem 89

Which of the following is the most correct expression for Heisenberg's uncertainty principle ?
(a) $\Delta x \cdot \Delta p=\frac{h}{4 \pi}$
(b) $\Delta x, \Delta p \geq \frac{h}{4 \pi}$
(c) $\Delta x \cdot \Delta p \leq \frac{h}{4 \pi}$
(d) $\Delta x \cdot \Delta v=\frac{h}{4 \pi}$

Ajay Singhal

Numerade Educator

Problem 90

The Heisenberg uncertainty principle can be applied to
(a) A cricket ball
(b) A foot ball
(c) A jet aeroplane
(d) An electron

Ajay Singhal

Numerade Educator

Problem 91

The wave character of electron was experimentally verified by
(a) De-Broglie
(b) A. Einstein
(c) Germer
(d) Schrodinger

Ajay Singhal

Numerade Educator

Problem 92

"The exact path of electron in 2p-orbital cannot be determined." The above statement is based upon
(a) Hund's Rule
(b) Bohr's Rule
(c) Uncertainty principle
(d) Aufbau principle

Ajay Singhal

Numerade Educator

Problem 93

Which series of subshells is arranged in the order of increasing energy for multi-electron atoms?
(a) $6 s, 4 f, 5 d, 6 p$
(b) $4 f, 6 s, 5 d, 6 p$
(c) $5 d, 4 f, 6 s, 6 p$
(d) $4 f, 5 d, 6 s, 6 p$

Ajay Singhal

Numerade Educator

Problem 94

The correct Schrodinger's wave equation for a electron with total energy $\mathrm{E}$ and potential energy $\mathrm{V}$ is given by
(a) $\frac{\partial^{2} \psi}{\partial x^{2}}+\frac{\partial^{2} \psi}{\partial y^{2}}+\frac{\partial^{2} \psi}{\partial z^{2}}+\frac{8 \pi^{2}}{m h^{2}}(E-V) \psi=0$
(b) $\frac{\partial^{2} \psi}{\partial x^{2}}+\frac{\partial^{2} \psi}{\partial y^{2}}+\frac{\partial^{2} \psi}{\partial z^{2}}+\frac{8 \pi m}{h^{2}}(E-V) \psi=0$
(c) $\frac{\partial^{2} \psi}{\partial x^{2}}+\frac{\partial^{2} \psi}{\partial y^{2}}+\frac{\partial^{2} \Psi}{\partial z^{2}}+\frac{8 \pi^{2} m}{h^{2}}(E-V) \psi=0$
(d) None of the above

Ajay Singhal

Numerade Educator

Problem 95

Wave mechanical model of the atom depends upon
(a) De-Broglie concept of dual nature of electron
(b) Heisenberg uncertainty principle
(c) Schrodinger uncertainty principle
(d) All

Ajay Singhal

Numerade Educator

Problem 96

$\psi^{2}(r, \theta, \phi)$ represents: (for schrodinger wave mechanical model)
(a) Amplitude of electron wave
(b) Probability density of electron
(c) Total probability of finding electron around nucleus
(d) Orbit

Ajay Singhal

Numerade Educator

Problem 97

Radial amplitude of electron wave can be represented by
(a) $R(r)$
(b) $R^{2}(r)$
(c) $4 \pi r^{2}$
(d) $4 \pi r^{2} R^{2}(r)$

Ajay Singhal

Numerade Educator

Problem 98

Arrange the orbitals of $\mathrm{H}$ -atom in the increasing order of their energy $3 p_{x}, 2 s, 4 d_{x y}, 3 s, 4 p_{z}, 3 p_{y}, 4 s$
(a) $2 s<3 s=3 p_{x}=3 p_{y}<4 s=4 p_{z}=4 d_{x y}$
(b) $2 s<3 s<3 p_{x}=3 p_{y}<4 s=4 p_{z}=4 d_{x y}$
(c) $2 s<3 s<3 p_{x}=3 p_{y}<4 s=4 p_{z}=4 d_{x y}$
(d) $2 s<3 s<3 p_{x}=3 p_{y}<4 s<4 p_{z}<4 d_{x y}$

Ajay Singhal

Numerade Educator

Problem 99

Which of the following orbitals in hydrogen atom is closer to the nucleus?
(a) $5 f$
(b) $6 d$
(c) $7 s$
(d) $7 p$

Ajay Singhal

Numerade Educator

Problem 100

The radii of maximum probability for $3 s, 3 p$ and $3 d$ electrons are in the order :
(a) $\left(r_{\max }\right)_{3 d}>\left(r_{\max }\right)_{3 p}>\left(r_{\max }\right)_{3_{s}}$
(b) $\left(r_{\max }\right)_{3 d}>\left(r_{\max }\right)_{3 s}>\left(r_{\max }\right)_{3 p}$
(c) $\left(r_{\max }\right)_{3_{5}}>\left(r_{\max }\right)_{3 n}>\left(r_{\text {max }}\right)_{3 d}$
(d) None of these

Ajay Singhal

Numerade Educator

Problem 101

The correct order of penetrating power of $3 s, 3 p, 3 d$ electrons is :
(a) $3 d>3 p>3 s$
(b) $3 s>3 p>3 d$
(c) $3 s>3 d>3 p$
(d) $3 d>3 s>3 p$

Ajay Singhal

Numerade Educator

Problem 102

The correct order of total number of node of atomic orbitals is:
(a) $4 f>6 s>5 d$
(b) $6 s>5 d>4 f$
(c) $4 f>5 d>6 s$
(d) $5 d>4 f>6 s$

Ajay Singhal

Numerade Educator

Problem 103

If the subsidiary quantum number of a subenergy level is 4, the maximum and minimum values of the spin multiplicities are :
(a) 9,1
(b) 10,1
(c) 10,2
(d) $4,-4$

Ajay Singhal

Numerade Educator

Problem 104

Which two orbitals are located along the axis, and not between the axis?
(a) $d_{x y}, d_{\alpha^{2}}$
(b) $d_{x y}, p_{x}$
(c) $d_{y z}, p_{x}$
(d) $p_{z}, d_{x^{2}-v^{2}}$

Ajay Singhal

Numerade Educator

Problem 105

In a set of degenerate orbitals the electrons distribute themselves to retain similar spins as far as possible. This statement is attributed to
(a) Pauli's exclusion principle
(b) Aufbau principle
(c) Hund's Rule
(d) Slater rule

Ajay Singhal

Numerade Educator

Problem 106

Which of the following rules could explain the presence of three unpaired electrons in N-atom?
(a) Hund's rule
(b) Aufbau's principle
(c) Heisenberg's uncertainty principle
(d) Pauli's exclusion principle

Ajay Singhal

Numerade Educator

Problem 107

Pauli's exclusion principle states that:
(a) Nucleus of an atom contains no negative charge
(b) Electrons move in circular orbits around the nucleus
(c) Electrons occupy orbitals of lowest energy
(d) All the four quantum numbers of two electrons in an atom cannot be equal.

Ajay Singhal

Numerade Educator

Problem 108

For which of the following sets of quantum numbers, an electron will have the highest energy? $n$
(a) $\begin{array}{cccc}n & l & m & s \\ 3 & 2 & 1 & -1 / 2 \\ 4 & 1 & -1 & +1 / 2\end{array}$
(b) 4 3
$\begin{array}{rc}m & s \\ -1 & +1 / 2 \\ 0 & -1 / 2\end{array}$
$\begin{array}{llllll}\text { (c) } & 4 & 1 & -1 & +1 / 2 & \text { (d) } & 5 & \end{array}$

Ajay Singhal

Numerade Educator

Problem 109

Which of the following statements concerning the four quantum numbers is false ?
(a) $n$ gives idea of the size of an orbital
(b) $l$ gives the shape of an orbital
(c) $\mathrm{m}$ gives the energy of the electron in the orbital
(d) s gives the direction of spin of the electron in an orbital

Ajay Singhal

Numerade Educator

Problem 110

Maximum number of electrons in a subshell is given by
(a) $(2 l+1)$
(b) $2(2 l+1)$
(c) $(2 l+1)^{2}$
(d) $2(2 l+1)^{2}$

Ajay Singhal

Numerade Educator

Problem 111

The orbital angular momentum of $3 p$ electron is :
(a) $\sqrt{3} h$
(b) $\sqrt{6} h$
(c) zero
(d) $\sqrt{2} \frac{h}{2 \pi}$

Ajay Singhal

Numerade Educator

Problem 112

The atomic orbitals are progressively filled in order of increasing energy. The principle is called as:
(a) Hund's rule
(b) Aufbau principle
(c) Exclusion principle
(d) de-Broglie rule

Ajay Singhal

Numerade Educator

Problem 113

The orbital diagram in which both the Pauli's exclusion principle and Hund's rule are violated, is:

Ajay Singhal

Numerade Educator

Problem 114

Which of the following elements is represented by the electronic configuration?
(a) Nitrogen
(b) Fluorine
(c) Oxygen
(d) Neon

Ajay Singhal

Numerade Educator

Problem 115

The ratio of magnetic moments of Fe (III) and Co (II) is :
(a) $\sqrt{5}: \sqrt{7}$
(b) $\sqrt{35}: \sqrt{15}$
(c) $7: 3$
(d) $\sqrt{24}: \sqrt{15}$

Ajay Singhal

Numerade Educator

Problem 116

If the electronic structure of oxygen atom is written as $1 s^{2}, 2 s^{2}$ it would violate
(a) Hund's rule
(b) Paulis exclusion principle
(c) Both Hund's and Pauli's principles
(d) None of these

Ajay Singhal

Numerade Educator

Problem 117

A compound of vanadium has a magnetic moment $(\mu)$ of $1.73 \mathrm{BM}$. If the vanadium ion in the compound is present as $\mathrm{V}^{x+}$, then, the value of $x$ is?
(a) 1
(b) 2
(c) 3
(d) 4

Ajay Singhal

Numerade Educator

Problem 118

$d^{6}$. configuration will result in total spin of:
(a) $\frac{3}{2}$
(b) $\frac{1}{2}$
(c) 2
(d) 1

Ajay Singhal

Numerade Educator

Problem 119

The probability of finding electrons in $d_{x y}$ orbital is :
(a) along $X$ - and $Y$ -axis
(b) along $X$ - and $Z$ -axis
(c) along $Y$ - and $Z$ -axis
(d) at an angle of $45^{\circ}$ with $X$ -axis

Check back soon!

Problem 120

The correct order of screening effects of $s, p, d, f$ sub-shells is :
(a) $s>p>d>f$
(b) $s<p<d<f$
(c) $d>p>s>f$
(d) $s>f>d>p$

Ajay Singhal

Numerade Educator

Problem 121

Read the following statements and choose the correct option:
(1) If the radius of the first Bohr orbit of hydrogen atom is $r$, then radius of $2^{\text {nd }}$ orbit of $\mathrm{Li}^{2+}$ would be $4 r$
(II) For s-orbital electron, the orbital angular momentum is zero
(a) only I is correct
(b) only II is correct
(c) both are correct
(d) bóth are incorrect

Ajay Singhal

Numerade Educator

Problem 122

The e quantum numbers of four electrons (e1 to e4) are given below :
$$
\begin{array}{ccccccccc}n & l & m & s & & n & l & m & s \\ 3 & 0 & 0 & +1 / 2 & e 2 & 4 & 0 & 0 & 1 / 2 \\ 3 & 2 & 2 & -1 / 2 & e 4 & 3 & 1 & -1 & 1 / 2\end{array}
$$ $\begin{array}{r}\text { The quar } \\ e 1 & n \\ e 3 & 3\end{array}$ The correct order of decreasing energy of these electrons is:
(a) $e 4>e 3>e 2>e 1$
(b) $e 2>e 3>e 4>e 1$
(c) $e 3>e 2>e 4>e 1$
(d) $e 1>e 4>e 2>e 3$

Aswathy M

Numerade Educator

Problem 123

The energy of an electron of $2 p_{y}$ orbital is
(a) Greater than $2 p_{x}$ orbital
(b) Less than $2 p_{s}$ orbital
(c) Equal to $2 \mathrm{~s}$ orbital
(d) Same as that of $2 p_{x}$ and $2 p_{z}$ orbital

Ajay Singhal

Numerade Educator

Problem 124

How do the energy gaps between successive electron energy levels in an atom vary from low to high $n$ values?
(a) All energy gaps are the same
(b) The energy gap decreases as $n$ increases
(c) The energy gap increases as $n$ increases
(d) The energy gap changes unpredictably as $n$ increases

Ajay Singhal

Numerade Educator

Problem 125

When an electron jumps from $\mathrm{L}$ to $\mathrm{K}$ shell -
(a) Energy is absorbed
(b) Energy is released
(c) Energy is neither absorbed nor released
(d) Energy is sometimes absorbed and some times released

Ajay Singhal

Numerade Educator

Problem 126

The number of unpaired valence electrons in an atom of phosphorus is :
(a) 0
(b) 2
(c) 3
(d) 4

Ajay Singhal

Numerade Educator

Problem 127

Which quantum number defines the orientation of orbital in the space around the nucleus?
(a) Principal quantum number $(n)$
(b) Angular momentum quantum number
(c) Magnetic quantum number $\left(m_{l}\right)$
(d) Spin quantum number $\left(m_{s}\right)$

Ajay Singhal

Numerade Educator

Problem 128

What is the maximum number of electrons in an atom that can have the quantum numbers $n=3$ and $l=2 ?$
(a) 2
(b) 5
(c) 6
(d) 10

Aswathy M

Numerade Educator

Problem 129

Which of the following statements about an electron with $m_{l}=+2$ is incorrect?
(a) The electron could be in the third shell
(b) The electron is in a non-spherical orbital
(c) The electron may have $m_{s}=\frac{1}{2}$
(d) The electron is not in a $d$ -orbital

Ajay Singhal

Numerade Educator

Problem 130

Which of the following set of quantum numbers is impossible for an electron?
(a) $n=1, l=0, m_{l}=0, m_{s}=+\frac{1}{2}$
(b) $n=9, l=7, m_{l}=-6, m_{s}=-\frac{1}{2}$
(c) $n=2, l=1, m_{l}=0, m_{s}=+\frac{1}{2}$
(d) $n=3, l=2, m_{l}=-3, m_{s}=+\frac{1}{2}$

Ajay Singhal

Numerade Educator

Problem 131

In a $3 d$ subshell, all the five orbitals are degenerate. What does it mean?
(a) All the orbitals have the same orientation.
(b) All the orbitals have the same shape.
(c) All the orbitals have the same energy.
(d) All the orbitals are unoccupied.

Ajay Singhal

Numerade Educator

Problem 132

Which of the following subshell can accomimodate as many. as 10 electrons?
(a) $2 d$
(b) $3 d$
(c) $3 d_{x \gamma}$
(d) $3 d_{-2}$

Ajay Singhal

Numerade Educator

Problem 133

Which of the following statements is correct for an electron having azimuthal quantum number $l=2 ?$
(a) The electron may be in the lowest energy shell.
(b) The electron is in a spherical orbital.
(c) The electron must have spin $m_{s}=+\frac{1}{2}$
(d) The electron may have a magnetic quantum number $=-1$

Ajay Singhal

Numerade Educator

Problem 134

Which of the following statements is incorrect?.
(a) The concepts of "penetration" and "shielding" are important in deciding the energetic ordering of orbitals in multi-electron atoms
(b) A wave-function can have positive and negative values
(c) "Radial nodes" can appear in radial probability distribution functions
(d) The absolute size of an orbital is given by the principal quantum number.

Ajay Singhal

Numerade Educator

Problem 135

For $4 p_{y}$ orbital: There are nodal plane $=\ldots$ and azimuthal quantum number $l=$
(a) 1,0
(b) 0,1
(c) 1,1
(d) 2,1

Ajay Singhal

Numerade Educator

Problem 136

Which of the following statement is correct?
(a) Number of angular nodes $=n-l-1$
(b) Number of radial nodes $=1$
(c) Total number of nodes $=n-1$
$\therefore$
(d) All

Ajay Singhal

Numerade Educator

Problem 137

Give the correct order of initials T (True) or $\mathbf{F}$ (False) for following statements.
(I) If electron has zero magnetic number, then it must be present in $s$ -orbital.
(II) $\ln [\|\quad\|$
III) Bohr's model can explain spectrum of the hydrogen atom.
(IV) A $d$ -orbital can accommodate maximum 10 electrons only.
(a) TTFF
(b) FFTF
(c) TFTT
(d) FFTT

Ajay Singhal

Numerade Educator

Problem 138

"No two electrons in an atom can have the same set of four quantum numbers". This principle was enunciated by
(a) Heisenberg
(b) Pauli
(c) Maxwell
(d) De-Broglie

Ajay Singhal

Numerade Educator

Problem 139

The orbital diagraram in which both the Pauli's exclusion principle and Hund's rule are violated is :

Ajay Singhal

Numerade Educator

Problem 140

It is not possible to explain the Pauli's exclusion principle with the help of this atom.
(a) B
(b) Be
(c) C
(d) $\mathrm{H}$

Ajay Singhal

Numerade Educator

Problem 141

The subshell that arises after $f$ subshell is called $g$ subshell. What is the total number of orbitals in the shell in which the $g$ subshell first occur?
(a) 9
(b) 16
(c) 25
(d) 36

Ajay Singhal

Numerade Educator

Problem 142

If hydrogen atom in ground state is passed-through an inhomogeneous magnetic field, the beam splits in two parts. This interaction with magnetic field shows:
(a) existence of ortho and para hydrogen
(b) existence of magnetic moment associated with orbital motion of electron
(c) existence of spin magnetic moment of electron
(d) existence of magnetic moment of proton

Ajay Singhal

Numerade Educator

Problem 143

In iron atom, how many electrons atom have $n=3$ and $l=2 ?$
(a) 2
(b) 4
(c) 6
(d) 8

Ajay Singhal

Numerade Educator

Problem 144

For similar orbitals having different values of $n:$
(a) the most probable distance increases with increase in $n$
(b) the most probable distance decreases with increase in $n$
(c) the most probable distance remains constant with increase in $n$
(d) none of these

Ajay Singhal

Numerade Educator

Problem 145

If $n$ and $l$ are principal and azimuthal quantum numbers respectively, then the expression for calculating the total number of electrons in any energy level is :
(a) $\sum_{l=0}^{l=n} 2(2 l+1)$
(b) $\sum_{i=1}^{l=n} 2(2 l+1)$
(c) $\sum_{l=0}^{1=n}(2 l+1)$
(d) $\sum_{l=0}^{t \pi n-1} 2(2 l+1)$

Ajay Singhal

Numerade Educator

Problem 146

Maximum number of total nodes is present in :
(a) $5 \mathrm{~s}$
(b) $5 p$
(c) $5 \mathrm{~d}$
(d) All have same number of nodes

Ajay Singhal

Numerade Educator

Problem 147

The possible correct set of quantum numbers for the unpaired electron of $\mathrm{Cl}$ atom is :
(a) $2,0,0,+\frac{1}{2}$
(b) $2,1,-1,+\frac{1}{2}$
(c) $3,1,1, \pm \frac{1}{2}$
(d) $3,0, \pm \frac{1}{2}$

Ajay Singhal

Numerade Educator

Problem 148

The aufbau principle implies that a new electron will enter an orbital for which :
(a) $n$ has a lower value
(b) $l$ has a lower value
(c) $(n+l)$ value is maximum
(d) $(n+l)$ value is minimum

Ajay Singhal

Numerade Educator

Problem 149

The orbital diagram in which aufbau principle is violated, is :

Ajay Singhal

Numerade Educator

Problem 150

Consider the following six electronic configurations (remàining inner orbitals are completely filled) and mark the incorrect option.
(a) Stability order : II > I > IV > III
(b) Order of spin multiplicity : $I V>I I I=I>I I$
(c) $\mathrm{V}$ does not violate all the three rules of electronic configuration
(d) If VI represents $A$ and $A^{+}$ when kept near a magnet, acts as diamagnetic substance.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 151

Which of the following set of quantum numbers belong to highest energy?
(a) $n=4, l=0, m=0, s=+\frac{1}{2}$
(b) $n=2, l=0, m=0, s=+\frac{1}{2}$
(c) $n=3, l=1, m=1, s=+\frac{1}{2}$
(d) $n=3, l=2, m=1, s=+\frac{1}{2}$

Ajay Singhal

Numerade Educator

Problem 152

A subshell $n=5, l=3$ can accommodate :
(a) 10 electrons
(b) 14 electrons
(c) 18 electrons
(d) None of these

Ajay Singhal

Numerade Educator

Problem 153

In H-atom energy of electron is determined by:
(a) only $n$
(b) $n, l$
(c) $n, l, m$
(d) all the four quantum numbers.

Ajay Singhal

Numerade Educator

Problem 154

How many electron(s) in an atom can have $n=3, l=2 ?$
(a) 1
(b) 2
(c) 5
(d) 10

Ajay Singhal

Numerade Educator

Problem 155

How many electrons in an atom can have $n=4, l=2, m=-2$ and $s=+\frac{1}{2} ?$
(a) 1
(b) 2
(c) 5
(d) 10

Ajay Singhal

Numerade Educator

Problem 156

Threshold frequency of a metal is $f_{0} .$ When light of frequency $v=2 f_{0}$ is incident on the metal plate, maximum velocity of $e^{-}$ emitted is $v_{1}$. When frequency of incident radiation is $5 f_{0}$, maximum velocity of emitted $e^{-}$ is $v_{2}$. Find ratio of $\frac{v_{1}}{2}$ :
(a) $1: 4$
(b) $1: 2$
(c) $2: 1$
(d) none of these

Ajay Singhal

Numerade Educator

Problem 157

Which orbital has only positive values of wave function at all distances from the nucleus:
(a) $1 s$
(b) $2 s$
(c) $2 p$
(d) $3 d$

Ajay Singhal

Numerade Educator

Problem 158

Four electrons in an atom have the sets of quantum numbers as given below. Which electron in at the highest energy level?
(a) $n=4, l=0, m_{l}=0, m_{s}=+1 / 2$
(b) $n=3, l=0, m_{l}=0, m_{s}=-1 / 2$
(c) $n=3, l=2, m_{l}=0, m_{s}=+1 / 2$
(d) $n=4, l=1, m_{l}=-1, m_{s}=-1 / 2$

Ajay Singhal

Numerade Educator

Problem 159

The set of quantum numbers, $n=3, l=2, m_{l}=0$
(a) describes an electron in a $2 s$ orbital
(b) is not allowed
(c) describes an electron in a $3 p$ orbital
(d) describes one of the five orbitals of same energy

Ajay Singhal

Numerade Educator

Problem 160

Consider the argon atom. For how many electrons does this atom have $m_{l}=1 ?$
(a) 1
(b) 6
(c) 4
(d) 2

Ajay Singhal

Numerade Educator

Problem 161

Consider the argon atom. For how many electrons does this atom have $m_{l}=1 ?$
(a) 1
(b) 6
(c) 4
(d) 2

Ajay Singhal

Numerade Educator

Problem 162

An orbital is occupied by an electron with the quantum numbers $n=4, l=1 .$ How many orbitals of this type are found in a multi-electron atom?
(a) $4 p, 3$
(b) $4 s, 1$
(c) $4 d, 5$
(d) $4 p, 6$

Ajay Singhal

Numerade Educator

Problem 163

Which of the following sets of quantum numbers describes the electron which is removed most easily from a potassium atom in its ground state?
(a) $n=3, l=1, m_{l}=1, m_{s}=-\frac{1}{2}$
(b) $n=2, l=1, m_{l}=0, m_{s}=-\frac{1}{2}$
(c) $n=4, l=0, m_{1}=1, m_{s}=+\frac{1}{2}$
(d) $n=4, l=0, m_{l}=0, m_{s}=+\frac{1}{2}$

Ajay Singhal

Numerade Educator

Problem 164

The subshell that arises after $f$ is called the $g$ subshell. How many electrons may occupy the $g$ subshell?
(a) 9
(b) 7
(c) 5
(d) 18

Ajay Singhal

Numerade Educator

Problem 165

Which of the following electron configurations is correct for iron, (atomic number 26)?
(a) $[\mathrm{Kr}] 4 s^{1} 3 d^{6}$
(b) $[\mathrm{Kr}] 4 s^{1} 3 d^{7}$
(c) $[\mathrm{Ar}] 4 s^{2} 3 d^{6}$
(d) $[\mathrm{Kr}] 4 s^{2} 3 d^{6}$

Ajay Singhal

Numerade Educator

Problem 166

Which of the following electron configurations is correct for copper, (atomic number 29$) ?$
(a) $[\operatorname{Ar}] 3 d^{10} 4 s^{1}$
(b) $[\mathrm{Kr}] 3 d^{9} 4 s^{1}$
(c) [Ar] $3 d^{9} 4 s^{2}$
(d) $[\mathrm{Kr}] 3 d^{10} 4 s^{1}$

Ajay Singhal

Numerade Educator

Problem 167

The electronic configurations of ${ }_{24} \mathrm{Cr}$ and ${ }_{29} \mathrm{Cu}$ are abnormal
(a) Due to extra stability of exactly half filled and exactly fully filled sub shells
(b) Because they belong to d-block
(c) Both the above
(d) None of the above

Ajay Singhal

Numerade Educator

Problem 168

Which of the following representation of excited states of atoms is impossible?
(a) $1 s^{1} 2 s^{1}$
(b) $[\mathrm{Ne}] 3 s^{2} 3 p^{3} 4 s^{1}$
(c) $[\mathrm{Ne}] 3 s^{2} 3 p^{6} 4 s^{1} 3 d^{6}(\mathrm{~d}) 1 s^{2} 2 s^{2} 2 p^{7} 3 s^{2}$

Ajay Singhal

Numerade Educator

Problem 169

Among the following representations of excited states of atoms which is impossible?
(a) $1 s^{1} 2 s^{1}$
(b) $[\mathrm{Ne}] 3 s^{2} 3 p^{3} 4 s^{1}$
(c) $1 s^{2} 2 s^{2} 2 p^{4} 3 s^{2}$
(d) $[\mathrm{Ne}] 3 s^{2} 3 p^{6} 4 s^{3} 3 d^{2}$

Ajay Singhal

Numerade Educator

Problem 170

Among the following series of transition metal ions, the one where all metal ions have same $3 d$ electronic configuration is:
(a) $\mathrm{Ti}^{2+}, \mathrm{V}^{3+}, \mathrm{Cr}^{4+}, \mathrm{Mn}^{5+}$
(b) $\mathrm{Ti}^{3+}, \mathrm{V}^{2+}, \mathrm{Cr}^{3+}, \mathrm{Mn}^{4+}$
(c) $\mathrm{Ti}^{+}, \mathrm{V}^{4+}, \mathrm{Cr}^{6+}, \mathrm{Mn}^{7+}$
(d) $\mathrm{Ti}^{4+}, \mathrm{V}^{3+}, \mathrm{Cr}^{2+}, \mathrm{Mn}^{3+}$

Ajay Singhal

Numerade Educator

Problem 171

Which of the following has the maximum number of unpaired electrons?
(a) $\mathrm{Mn}$
(b) Ti
(c) $\mathrm{V}$
(d) $\mathrm{Al}$

Ajay Singhal

Numerade Educator

Problem 172

Which of the following orbitals has two spherical nodes?
(a) $2 \mathrm{~s}$
(b) 45 .
(c) $3 d$
(d) $6 f$

Ajay Singhal

Numerade Educator

Problem 173

Wave function of an orbital is plotted against the distance from nucleus. The graphical representation is of:
(a) $1 s$
(b) $2 s$
(c) $3 s$
(d) $2 p$

Ajay Singhal

Numerade Educator

Problem 174

The Schrodinger wave equation for hydrogen atom is
$$
\Psi_{2 s}=\frac{1}{4 \sqrt{2 \pi}}\left(\frac{1}{a_{0}}\right)^{3 / 2} \cdot\left(2-\frac{r}{a_{0}}\right) e^{-r / \infty}
$$
where $a_{0}$ is Bohr's radius. If the radial node in $2 s$ be at $r_{0}$, then $r_{0}$ would be equal to :
(a) $\frac{a_{0}}{2}$
(b) $2 a_{0}$
(c) $\sqrt{2} a_{0}$
(d) $\frac{a_{0}}{\sqrt{2}}$

Ajay Singhal

Numerade Educator

Problem 175

The Schrodinger wave equation for hydrogen atom is
$$
\Psi(\text { radial })=\frac{1}{16 \sqrt{4}}\left(\frac{z}{a_{0}}\right)^{3 / 2}\left[(\sigma-1)\left(\sigma^{2}-8 \sigma+12\right)\right] e^{-\sigma / 2}
$$
where $a_{0}$ and $Z$ are the constant in which answer can be expressed and $\sigma=\frac{2 Z r}{a_{0}}$ minimum and maximum position of radial nodes from nucleus are ......respectively. $\therefore .$
1
$\begin{array}{llll}\text { (a) } \frac{a_{0}}{Z}, \frac{3 a_{0}}{Z} & \text { (b) } \frac{a_{0}}{2 Z}, \frac{a_{0}}{Z} & \text { (c) } \frac{a_{0}}{2 Z}, \frac{3 a_{0}}{Z} & \text { (d) } \frac{a_{0}}{2 Z}, \frac{4 a_{0}}{Z}\end{array}$

Ajay Singhal

Numerade Educator