Force and Laws of Motion — Science STD 9 — Question

How is cream separated form milk?

What is the role of nuclear pores in a cell?

Explain why, we can easily move our hand in air but to do the same through a plank of wood, we need a karate expert.

What is the significance of the symbol of an element? Explain with the help of an example.

Suppose a planet exists whose mass and radius both are half that of the earth. The acceleration due to gravity on the surface of this planet will be double? Justify.

Explain any one method of crop production which ensures high yield.

We eat food composed of all the nutrients like carbohydrates, proteins, fats, vitamins, minerals and water. After digestion, these are absorbed in the form of glucose, amino acids, fatty acids, glycerol, etc.
What mechanisms are Involved in absorption of digested food and water?

Can we apply Newton’s third law to the gravitational force? Explain your answer.

The scientists now say that there are actually five states of matter A, B, C, D and E. The state A has a fixed volume but no fixed shape. The state B can be compressed very easily by applying pressure and state C has a fixed shape as well as a fixed volume. The state D is mixture of free electrons and ions whereas state E is named after an Indian scientist and a famous physicist.

1. Name the physical states (i) A (ii) B (iii) C (iv) D, and (v) E.
2. Name one substance belonging to state C which can directly change into vapours on heating. What is this process known as?
3. Name one substance which normally belongs to state B but whose solid form changes directly into gaseous state.
4. Name the most common substance belonging to state A.
5. Which state of matter makes the sum and other stars to glow.