1. Which rocks are formed by the aliteration of pre-existing rocks by great heat or pressure?

2. The unit of home electricity energy consumption is:

3. The speed of sound in dry air at 20C is about

4. The ozone layer protects the earth from rays sent by the sun:

5. unit of length equal to the average distance between the earth and sun is called

6. The density of water is greatest at:

7. An electric current can produce

8. The most abundant in sea water are

9. The time light takes from Sun to reach Earth is:

10. Light from Sun travels a distance before it reaches Earth:

11. Sun is a:

12. The age of the solar system is

13. An eclipse of the sun occurs when

14. The of light in vacuum is about

15. When sound is reflected from floor, ceiling or a wall, it mixes with the origial sound and change its complexion, it is called as

16. The planet of the solar system which has maximum numbers of Moon is:

17. The magnet always points in the same direction, if move freely i.e. towards nort and south poles, because of:

18. The most abundant natural Iron oxides are

19. Which one of the following statements is true:

20. The most suitable thermometer for measuring the boiling point of water is: