Tissues — Science STD 9 — Question

How will you separate a mixture of sodium chloride and sand?

Define valency by taking examples of silicon and oxygen.

How does the water kept in an earthen pot (matka) become cold during summer?

How will you separate a mixture of iron filings and sulphur powder without using carbon disulphide?

Describe a method for separating a mixture of iron filings and sulphur powder other than that by using a magnet.

Give any two functions performed by epithelial tissue.

What is the momentum in kgm/s of a 10kg car travelling at (a) 5m/s (b) 20cm/s, and (c) 36km/h?

Explain why particles of a colloidal solution do not settle down when left undisturbed, while in the case of a suspension they do.

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?

If you are provided with some vegetables to cook. You generally add salt into the vegetables during cooking process. After adding salt, vegetables release water. What mechanism is responsible for this?