Q10 of 22 Page 33

Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue coloured crystals got separated (step II). Step I and step II are:

Crystallisation is a physical change and also can be reversed. Therefore, both the steps are physical change.

More from this chapter

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8

Paheli’s mother made a concentrated sugar syrup by dissolving sugar in hot water. On cooling, crystals of sugar got separated. This indicates a-

 9

Which of the following statement is incorrect for a chemical reaction?

 11

State whether the following statements are true or false:

(a) When a candle burns, both physical and chemical changes take place.


(b) Anaerobic bacteria digest animal waste and produce biogas.


(c) Ships suffer a lot of damage though they are painted.


(d) Stretching of rubber band is not a physical change.

 12

Melting of wax is a change where a solid changes to liquid state. Give one more such change which you observe in your surroundings.