Q21. What are igneous rocks?
Q22. What are minerals?
Q23. Limestone is changed into marble. Give reason?
Q24. Write about the deepest mine in the world.
Q25. Why we cannot go to the centre of the earth?
Q26. What do you mean by a rock cycle?
Q27. What happens to igneous and sedimentary rocks when they are subjected to great heat and pressure?
Q28. How are minerals useful to mankind?
Q29. What are the uses of rocks?
Q30. How are extrusive and intrusive rocks formed?
Q31. Differentiate between sial and sima.
Q32. Sedimentary rocks are formed from sediments. Give reason.
Q33. What do you know about earth's interior?
Q34. Write a note on various types of rocks?