1. Nuclear sizes are expressed in a unit named ?
2. Light year is a unit of ?
3. Light from the Sun reaches us in nearly ?
Ans. 8 minutes
4. Metals are good conductors of electricity because ?
Ans. They contain free electrons
5. Sound waves in air are ?
6. Magnetism at the centre of a bar magnet is ?
7. RADAR is used for ?
Ans. Detecting and locating the positions of object
8. Sound of frequency below 20 Hz is called ?
9. Light Emitting Diodes (LED) is used in fancy electronic devices such as toys emit ?
Ans. Visible light
10. Optical fibre works on the ?
Ans. Total Internal reflection