Gravitation — Science STD 9 — Question

The substance X normally exists in a physical state which can flow easily but does not fill its vessel completely. It also turns anhydrous copper sulphate blue. When substance X is cooled excessively, it changes into a substance Y which has a fixed shape as well as a fixed volume. If, however, the substance X is heated strongly, it changes into a substance Z which has neither a fixed shape nor a fixed volume.

1. Name the substances (i) X (ii) Y and (iii) Z.
2. What is the process of conversion of X into Y known as?
3. At which temperature X gets converted into Y?
4. What is the process of conversion of X into Z known as?
5. At which temperature X gets converted into Z?

State three reasons why you think air is a mixture and water is a compound.

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 why, it is dangerous to jump out of a moving bus.

What is meant by the term ‘acceleration’ State the SI unit of acceleration.

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

Which object is vibrating when the following sounds are produced?

1. The sound of a sitar.
2. The sound of table.
3. The sound of a tuning fork.
4. The buzzing of a bee or mosquito.
5. The sound of a flute.