Colours of thin films are due to?
1). dispersion of light
2). interference of light
3). absorption of light?
4). scattering of light
3. Beta rays emitted by a radioactive material are
4. After removing two electrons from helium atom it become?
5. When a vibrating tuning fork is placed on a table a loud sound is heard. This is due to :
6. Mercury is the _______ planet from the Sun.
7. The unit of Planck's constant is
9. The reason for a swimming pool to appear less deep than the actual depth is