When a body is earth connected, electrons from the earth flow into the body. This means the body is

• charged negatively

• an insulator

• uncharged

• charged positively

The electron in a hydrogen atom makes a transition from n = n₁ to n = n₂ state. The time period of the electron in the initial state (n₁) is eight times that in the final state (n₂). The possible values of n₁ and n₂ are

• n₁ = 8, n₂ = 1

• n₁ = 4, n₂ = 2

• n₁ = 2, n₂ = 4

• n₁ = 1, n₂ = 8

The energy that should be added to an electron to reduce its de-Broglie wavelength from 1 nm to 0.5 nm is

• four times the initial energy

• equal to the initial energy

• twice the initial energy

• thrice the initial energy

Bohr's atom model assumes

• the nucleus is of infinite mass and is at rest

• electrons in a quantized orbit will not radiate energy

• mass of electron remains constant

• all the above conditions

White light is passed through a dilute solution of potassium permanganate. The specturm produced by the emergent light is

• band emission spectrum

• line emission spectrum

• band absorption spectrum

• line absorption spectrum

If λ₁ and λ₂ are the wavelengths of the first members of the Lyman and Paschen series respectively, then λ₁ : λ₂ , is 

• 1 : 3

• 1 : 30

• 7 : 50

• 7 : 108

Which of the following figures represents the variation of particle momentum and associated de-Broglie wavelength ?

48.

Electrons in a certain energy level n = n₁ can emit 3 spectral lines. When they are in another energy level, n = n₂, they can emit 6 spectral lines. The orbital speed of the electrons in the orbits are in the ratio

• 4 : 3

• 3 : 4

• 2 : 1

• 1 : 2

The de-Broglie wavelength of a proton (charge = 1.6 x 10^-19 C, mass = 16 x 10^-27 kg) accelerated through a potential difference of 1 kV is

• $600 \stackrel{\circ }{\mathrm{A}}$

• $0.9 \times {10}^{-12} \mathrm{m}$

• $7 \stackrel{\circ }{\mathrm{A}}$

• 0.9 nm

In Raman effect, Stokes' lines are spectral lines having

• frequency greater than that of the original line

• wavelength equal to that of the original line

• wavelength less than that of the original line

• wavelength greater than that of the original line