Nuclei — Physics STD 12 Science — Question

In a p-n junction with open ends:

1. There is no systematic motion of charge carriers.
2. Holes and conduction electrons systematically go from the p-side to the n-side and from the n side to the p-side respectively.
3. There is no net charge transfer between the two sides.
4. There is a constant electric field near the junction.

When hydrogen atom is in its first excited level, it’s radius is:

Light of wavelength 4000 Å is incident on a sodium surface for which the threshold wave length of photo – electrons is 5420 Å. The work function of sodium is (a) 4.58 eV(b) 2.29 eV(c) 1.14 eV(d) 0.57 eV

The unit for molar susceptibility is

A solid floats in a liquid in a partially dipped position.

1. The solid exerts a force equal to its weight on the liquid.
2. The liquid exerts a force of buoyancy on the solid which is equal to the weight of the solid.
3. The weight of the displaced liquid equals the weight of the solid.
4. The weight of the dipped part of the solid is equal to the weight of the displaced liquid.

An ice cube is suspended in vacuum in a gravity free hall. As the ice melts it.

1. Will retain its cubical shape.
2. Will change its shape to spherical.
3. Will fall down on the floor of the hall.
4. Will fly up.

How many coulombs of electricity must pass through acidulated water to liberate 22.4 litres of hydrogen at N.T.P.?

The momentum of a photon of energy hv will be (a) hv (b) hv/c (c) hvc      (d) h/v