Tamil Nadu (English Medium) Plus 2 Biology Science Study Materials, Online Learning, Question Papers, Classnotes, Practice Test, MCQ | Smartindia Educational Program : www.smartindia.net.in

An α-particle of energy 5 MeV is scattered through 180^{o} by a fixed uranium nucleus. The distance of the closest approach is of the order of

(A)

1 Å

(B)

10^{-10 }cm

(C)

10^{-12 }cm

(D)

10^{-15} cm

Question-2

The Bohr model of atoms

(A)

assumes that the angular momentum of electrons is quantized

(B)

uses Einstein’s photoelectric equation

(C)

predict continuous emission spectra for atoms

(D)

predicts the same emission spectra for all types of atoms

Question-3

When hydrogen atom is in its first excited level, its radius is

(A)

four times, its ground sate radius

(B)

twice, its ground state radius

(C)

same as its ground state radius

(D)

half of its ground state radius

Question-4

When electron jumps from n = 4 to n = 2 orbit, we get

(A)

second line of Lyman series

(B)

second line of Balmer series

(C)

second line of Paschen series

(D)

an absorption line of Balmer series

Question-5

When a hydrogen atom is raised from the ground state to an excited state

(A)

potential energy decreases and kinetic energy increases

(B)

potential energy increases and kinetic energy decreases

(C)

Both kinetic energy and potential energy decrease

(D)

Absorption spectrum

Question-6

The total energy of electron in the ground state of hydrogen atom is -13.6 eV. The kinetic energy of an electron in the first excited state is

(A)

3.4 eV

(B)

6.8 eV

(C)

13.6 eV

(D)

1.7 eV

Question-7

Which of the following transitions in a hydrogen atom emits of the highest frequency?

(A)

n = 1 to n = 2

(B)

n = 2 to n = 6

(C)

n = 2 to n = 1

(D)

n = 6 to n = 2

Question-8

In the Bohr’s model of a hydrogen atom, the centripetal force is furnished by the Coulomb attraction between the proton and the electron. If a_{0} is the radius of the ground state orbit, m is the mass and e is the charge on the electron, ε_{0} is the vacuum permittivity, the speed of the electron is

(A)

zero

(B)

(C)

(D)

Question-9

To explain theory of hydrogen atom, Bohr considered

(A)

quantisation of linear momentum

(B)

quantisation of angular momentum

(C)

quantisation of angular frequency

(D)

quantisation of energy

Question-10

The energy required to excite hydrogen atom from n = 1 to n = 2 state is 10.2 eV. What is the wavelength emitted when it returns to ground state?

(A)

1020 × 10^{-10 }m

(B)

1220 × 10^{-10 }m

(C)

1320 × 10^{-10} m

(D)

920 × 10^{-10} m

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