JEE Chemistry Structure of Atoms MCQs C

Question. For which element, the valence electron will be present in the highest energy orbital
(a) 21^Sc
(b) 16^S
(c) 3^Li
(d) 20^Ca

Answer: A

Question. Which of the following statements are not correct about electromagnetic radiation ?
(i) Electromagnetic waves require medium to travel.
(ii) Different electromagnetic radiations travel at same speed in vaccum.
(iii) The oscillating electric and magnetic fields produced by oscillating charged particles are perpendicular to each other, but not to the direction of propagation.
(iv) The oscillating electric field and magnetic field are perpendicular to each other, and also to the direction of propagation.
(a) (i) and (iii)
(b) (i), (ii) and (iii)
(c) (ii) and (iii)
(d) (i) and (iv)

Answer: A

Question. Which of the following statement(s) is/are incorrect regarding photoelectric effect?
(i) The number of electrons ejected is proportional to the intensity of light.
(ii) There is some time lag between the striking of light beam on the metal surface and the ejection of electrons.
(iii) The kinetic energy of ejected electrons depends upon the brightness of light.
(iv) The kinetic energy of the ejected electron is proportional to the frequency of the incident radiation.
(a) (ii) and (iii)
(b) (ii) and (iv)
(c) (i) and (ii)
(d) (ii) only

Answer: A

Question. Which of the following statements of quantum mechanics was in agreement with Bohr’s model?
(i) The path of an electron in an atom can never be determined accurately.
(ii) The energy of electrons in atom is quantized i.e., can only have specific values.
(iii) An orbital cannot contain more than two electrons.
(a) Only (ii)
(b) Only (i)
(c) (i) and (ii)
(d) (ii) and (iii)

Answer: A

Question. Which of the following statements concerning the quantum numbers are correct ?
(i) Angular quantum number determines the threedimensional shape of the orbital.
(ii) The principal quantum number determines the orientation and energy of the orbital.
(iii) Magnetic quantum number determines the size of the orbital.
(iv) Spin quantum number of an electron determines the orientation of the spin of electron relative to the chosen axis.
The correct set of option is
(a) (i) and (iv)
(b) (ii), (iii) and (iv)
(c) (i) and (ii)
(d) (iii) and (iv)

Answer: A

Question.
Assertion : The position of an electron can be determined exactly with the help of an electron microscope.
Reason : The product of uncertainty in the measurement of its momentum and the uncertainty in the measurement of the position cannot be less than a finite limit.
(a) Assertion is incorrect, reason is correct
(b) Assertion is correct, reason is incorrect
(c) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(d) Assertion is correct, reason is correct; reason is a correct explanation for assertion

Answer: A

Question.
Assertion : All isotopes of a given element show the same type of chemical behaviour.
Reason : The chemical properties of an atom are controlled by the number of electrons in the atom.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct

Answer: A

Question.
Assertion : Black body is an ideal body that emits and absorbs radiations of all frequencies.
Reason : The frequency of radiation emitted by a body goes from a lower frequency to higher frequency with an increase in temperature.
(a) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(b) Assertion is correct, reason is incorrect
(c) Assertion is incorrect, reason is correct.
(d) Assertion is correct, reason is correct; reason is a correct explanation for assertion
(b) Assertion is incorrect, reason is correct

Answer: B

Question. What is the ratio of mass of an electron to the mass of a proton?
(a) 1 : 1837
(b) 1 : 2
(c) 1 : 1
(d) 1 : 3

Answer: C

Question. In which of the following the amount of deviation from their path in the presence of electric and magnetic field will be maximum?
(a) N^3–
(b) N
(c) N^–
(d) N^2–

Answer: B

Question. The deflection of the particles from their path in presence of electric and magnetic field will be maximum in which of the following
(a) He
(b) N
(c) O
(d) U

Answer: A

Question. If the alpha-particles are projected against the following atoms Fe, Be, Mg, Al then increasing order in which the alpha-particle feel repulsion will be
(a) Be, Mg, Al, Fe
(b) Mg, Al, Mg, Fe
(c) Be, Al, Mg, Fe
(d) Al, Mg, Fe, Be

Answer: A

Question. Chlorine exists in two isotopic forms, C1-37 and C1-35 but its atomic mass is 35.5. This indicates the ratio of C1-37 and C1-35 is approximately
(a) 1 : 3
(b) 1 : 2
(c) 1 : 1
(d) 3 : 1

Answer: A

Question. The number of electrons, neutrons and protons in a species are equal to 10, 8 and 8 respectively. The proper symbol of the species is
(a)  ¹⁸Ne₁₀
(b)  ¹⁶O₈
(c) Both
(d) None of these

Answer: A

Question. Arrange the electromagnetic radiations a, b, c, d and e in increasing order of energy. Frequencies of a, b and c are 10¹⁵, 10¹⁴ and 10¹⁷ respectively whereas wavelength of (d) and (e) are 350 nm and 100 nm respectively ?
(a) b, d, a, e, c
(b) a, b, d, e, c
(c) a, b, c, d, e
(d) None of these

Answer: A

Question. The Bohr orbit radius for the hydrogen atom (n = 1) is approximately 0.530 Å. The radius for the first excited state (n = 2) orbit is (in Å)
(a) 2.12
(b) 1.06
(c) 0.13
(d) 4.77

Answer: A

Question. According to Bohr’s theory the energy required for an electron in the Li²⁺ ion to be emitted from n = 2 state is (given that the ground state ionization energy of hydrogen atom is 13.6 eV)
(a) 30.6 eV
(b) 61.2 eV
(c) 13.6 eV
(d) 10.2 eV

Answer: A

Question. Among species H, Li²⁺, He⁺, Be³⁺ and Al³⁺ Bohr’s model was able to explain the spectra of
(a) all other species except Al³⁺
(b) all other species except Be³⁺
(c) None of these
(d) All of these

Answer: A

Question. Which of the following levels of H and He⁺ have same energy respectively ?
(A) 1, 2 (B) 3, 4
(C) 2, 4 (D) 3, 6
(a) A, C and D
(b) A and B
(c) A and D
(d) C and D

Answer: D

Question. The ratio between kinetic energy and the total energy of the electrons of hydrogen atom according to Bohr’s model is
(a) 1 : – 1
(b) 2 : 1
(c) 1 : 1
(d) 1 : 2

Answer: A

Question. In hydrogen atomic spectrum, a series limit is found at 12186.3 cm^–1. Then it belong to
(a) Paschen series
(b) Lyman series
(c) Balmer series
(d) Brackett series

Answer: A

Question. Which transition in the hydrogen atomic spectrum will have the same wavelength as the transition, n = 4 to n = 2 of He⁺ spectrum?
(a) n = 2 to n = 1
(b) n = 3 to n = 2
(c) n = 4 to n = 3
(d) n = 4 to n = 2

Answer: A

Question. Arrange the following elements in the order of ease of detection of wave properties, in the de Broglie experiment.
H, Li, Be, B, K
(a) H > Li > Be > B > K
(b) H < Be, B < Li < K
(c) H > Li > K > Be > B
(d) H < Li < Be < B < K

Answer: A

Question. Calculate the velocity of ejected electron from the metal surface when light of frequency 2 × 10¹⁵ Hz fall on the metal surface and the threshold frequency is 7 × 10¹⁴ Hz for metal ?
(a) 1.37 × 10⁶
(b) 1.45 × 10⁷
(c) 1.26 × 10⁶
(d) 1.37 × 10⁷

Answer: A

Question. The velocity of particle A is 0.1 ms^–1 and that of particle B is 0.05 ms^–1. If the mass of particle B is five times that of particle A, then the ratio of de Broglie wavelengths associated with the particles A and B is
(a) 5 : 2
(b) 3 : 4
(c) 2 : 5
(d) 6 : 4

Answer: A

Question. Two fast moving particles X and Y are associated with de Broglie wavelengths 1 nm and 4 nm respectively. If mass of X in nine times the mass of Y, the ratio of kinetic energies of X and Y would be
(a) 16 : 9
(b) 9 : 1
(c) 3 : 1
(d) 5 : 12

Answer: A

Question. The measurement of the electron position is associated with an uncertainty in momentum, which is equal to 1×10^–18 g cm s^–1. The uncertainty in electron velocity is, (mass of an electron is 9 × 10^{– 28} g)
(a) 1 × 10⁹ cm s^–1
(b) 1 × 10⁶ cm s^–1
(c) 1 × 10¹¹ cm s^–1
(d) None of these

Answer: A

Question. An electron has principal quantum number 3. The number of its (i) subshells and (ii) orbitals would be respectively
(a) 3 and 9
(b) 3 and 5
(c) 3 and 7
(d) 2 and 5

Answer: A

Question. Which of the following statements about the electron is incorrect?
(a) The mass of electron is equal to the mass of neutron
(b) It is negatively charged particle
(c) It is a basic constituent of all atoms.
(d) It is a constituent of cathode rays

Answer: A