1. Planet and their moons are the examples of

2. The percentage of nitrogen in the air is

3. A machine makes the work

4. The power house of cell is called

5. Which organisms are called producers

6. Sound can not travel in vacuum because

7. What are tissues

8. Which gas is used in photosynthesis

9. which statement is true

10. The main components of environment are called

11. Which of them is the most important machine

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

13. Which of them is best solvent

14. Which of them is energy of the sun

15. The living things which eat Grass are called

16. What is the speed of sound in air

17. A solution consisting of two substance is called

18. What is called universal solvent

19. Animals cells can not prepare their food because

20. The living things which eat meat are called