# Physics Class12th Chapter12 ATOMS VVI Objective Question

Q.1. Which series comes in visible region of hydrogen spectrum ?

(A) Lyman series

(B) Blamer series

(C) Paschem series

(D) Brackett series

Ans :- (B)

Q.2. The minimum angular momentum of electron in Hydrogen atom will be

(A) h/π Js

(B) nh/2π Js

(C) hπ Js

(D) 2πh Js

Ans :- (B)

Q.3. The number of photons of frequency 10¹⁴ Hz in radiation of 6.62 J will be

(A) 10¹⁰

(B) 10¹⁵

(C) 10²⁰

(D) 10²⁵

Ans :- (C)

Q.4. The binding energy of the hydrogen atom is

(A) infinite

(B) zero

(C) 1 eV

(D) – 13.6 eV

Ans :- (D)

Q.5. The energy of an electron in the hydrogen atom is equal to

(A) E = m

(B) E = m²

(C) E = mc²

(D) E = 1/2 mc²

Ans :- (C)

Q.6. The SI unit of Rydberg constant is

(A) m⁻¹

(B) m

(C) s⁻¹

(D) s

Ans :- (A)

Q.7. When an atom of helium loses two electrons, It becomes

(A) α – particle

(B) neutron

(C) proton

(D) none of these

Ans :- (A)

Q.8. The energy needed to make an electron transit from ground state to the first excited state in hydrogen atom is

(A) 10.2 eV

(B) 13.6 eV

(C) 1.2 eV

(D) none of these

Ans :- (A)

Q.9. What is the energy of He⁺ electron in first orbit ?

(A) 40.8 eV

(B) – 27.2 eV

(C) – 54.4 eV

(D) – 13.6 eV

Ans :- (C)

Q.10. The ground state energy of hydrogen atom is – 13.6 eV . What is the potential energy of the electron in this state ?

(A) 0 eV

(B) – 27.2 eV

(C) 1 eV

(D) 2 eV

Ans :- (B)

Q.11. Dimensional formula of Ryberg’s constant is

(A) [M⁰L⁻¹T⁰]

(B) [MLT⁻¹]

(C) [M⁰LT⁰]

(D) [M⁰L⁰T⁰]

Ans :- (A)

Q.12. Which of the following atoms has the lowest ionisation potential

(A) ₇N¹⁴

(B) ₅₅Cs¹³³

(C) ₁₈Ar⁴⁰

(D) ₈O¹⁶

Ans :- (B)

Q.13. The ratio of the size of an atom to that of nucleus is approximately equal to

(A) 10⁴

(B) 10⁻⁵

(C) 10⁻³

(D) 10⁸

Ans :- (A)

Q.14. Which of the following element is without neutron ?

(A) Gold

(B) hydrogen

(C) helium

(D) oxygen

Ans :- (B)

Q.15. Which one is not divisible ?

(A) atom

(B) nucleus

(C) photon

(D) none of these

Ans :- (C)

Q.16. The largest wavelength in Balmer series of Hydrogen spectrum will be

(A) 6557 A

(B) 1216 A

(C) 4800 A

(D) 5600 A

Ans :- (A)

Q.17. If the energy of photon is E, it is equivalent to a mass

(A) E/C

(B) E×C²

(C) E/C²

(D) C²/E

Ans :- (C)

Q.18. The energy equired to send the electron from the first excitation orbit to the second orbit is

(A) 3.4 eV

(B) 10.2 eV

(C) 12.1 eV

(D) 13.6 eV

Ans :- (B)

Q.19. Wavelength of Kα line of X – ray spectra varies with atomic number as

(A) α ∞ Z

(B) λ ∞ √Z

(C) λ ∞ 1/Z²

(D) λ ∞ 1/√Z

Ans :- (C)

Q.20. The number of protons in an atom of atomic number Z and mass number A is

(A) Z

(B) A

(C) A – Z

(D) A + Z

Ans :- (A)

Q.21. The helium atom does not contain

(A) two protons

(B) two neutrons

(C) two electrons

(D) six nucleons

Ans :- (D)