(a) Illustrate with an example that physical and chemical changes can takes place together
.
 (b) Which of the following are chemical changes :
(i) Mixing of Iron filings and sand
 (ii) Growth of plant
 (iii) Rusting of Iron (iv) Freezing of water

  Define solid state of matter. State properties associated with this state.

 Illustrate with an example that evaporation cause cooling.

In which of the following substances you expect strongest and in which weakest force of attraction between the particles : alcohol, water, sodium chloride, carbondioxide. Give reason for your answer.

Write your observations when the following processes take place
 (a) an aqueous solution of sugar is heated to dryness.
 (b) a saturated solution of potassium chloride prepared at 60C is allowed to cool at room temperature.
 (c) a mixture of iron filings and sulphur powder is heated strongly.
 (d) A beam of light is passed through a colloidal solution.
 (e) dil – HCl is added to the mixture of iron and sulphur.

Describe an activity to show that air contains water vapours

(a) Define evaporation. Out of nylon and cotton clothes, which will be more comfortable during summer and why ? (b)
Is evaporation and boiling are same ? If not then why ?