Is Matter Around us Pure

Is matter around us pure Worksheet-7

11. A shining thick liquid is often used in glass thermometers. Name it.

A. Cesium          B. Gallium         C. Mercury        D. Bromine

12. A ______ knife is quite often used for cutting glass.

A. Diamond      B. Silicon           C. Fullerene      D. Carbon fibre

13. Is fresh air which we breathe in, a pure substance?

A. Yes                 B. No                  C. Depends on the area

Is matter around us pure Worksheet-8

21. What will happen if a colloidal solution of sulphur is centrifuged in a centrifugal machine for sometime?

A. Yellow coloured sulphur will float at the surface of solution

B. Sulphur will dissolve completely forming true solution

C. Yellow ppt of sulphur will be formed and supernatant solution will be colourless

D. The solution will become dark yellow in colour due to dissolution of more sulphur in it

22. Rusting of iron is a ______change.

A. Chemical

B. Physical

Is matter around us pure Worksheet-9

1. State one property in which a solution of sugar in water resembles a mixture of sugar and sand and one property in which it differs from it.

2. Account for - Fresh air cannot be regarded as a pure substance.

3. The table given below shows number of grams of five different solids dissolving in 100 g of the solvents : water, alcohol and chloroform (all at 20°C).

(a) Which solid dissolves best in water at 20°C ?

(b) Which solid is maximum soluble in alcohol ?