Improvement in Food Resources — Science STD 9 — Question

When a gas jar containing air is inverted over a gas jar containing bromine vapour, the red-brown bromine vapour diffuse into air. Explain how bromine vapour diffuse into air.

Explain the methods of controlling insect pests.

Name the type of tissue present, where transportation of substances occurs through the selectively permeable membrane.

Define green revolution, what are the common objectives of crop improvement?

If a balloon filled with air and its mouth untied, is released with its mouth in the downward direction, it moves upwards. Why?

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.

Name the process associated with the following:
Milk is churned to separate cream from it.

When is the pressure on the ground more-when a man is walking or when a man is standing? Explain.

Describe how the gravitational force between two objects depends on the distance between them.