1

Numerical
The atomic masses of He and Ne are 4 and 20 a.m.u., respectively. The value of the de Broglie wavelength of He gas at –73oC is “M” times that of the de Broglie wavelength of Ne at 727oC. M is

2

### IIT-JEE 2011

Numerical
The work function ( φ ) of some metals is listed below. The number of metals which will show photoelectric effect when light of 300 nm wavelength falls on the metal is
Metal Li Na K Mg Cu Ag Fe Pt W
Ф (eV) 2.4 2.3 2.2 3.7 4.8 4.3 4.7 6.3 4.75

3

### IIT-JEE 2011

Numerical
The maximum number of electrons that can have principal quantum number, n = 3, and spin quantum number, ms = − 1/2 , is

4

### IIT-JEE 1994

Numerical
Find out the number of waves made by a Bohr electron in once complete revolution in its 3rd orbit?