1. The percentage of nitrogen in the air is

2. The living things which eat meat are called

3. Which of them is the most important machine

4. The main components of environment are called

5. The living things which eat both plants and meat are called

6. Animals cells can not prepare their food because

7. What is called universal solvent

8. A solution consisting of two substance is called

9. Planet and their moons are the examples of

10. A machine makes the work

11. What is the speed of sound in air

12. which statement is true

13. Sound can not travel in vacuum because

14. Which of them is energy of the sun

15. Which gas is used in photosynthesis

16. Which of them is best solvent

17. The power house of cell is called

18. The living things which eat Grass are called

19. What are tissues

20. Which organisms are called producers