The chemical reaction between quicklime and water is characterised by :
(a) evolution of hydrogen gas

(b) formation of slaked lime precipitate

(c) change in temperature of mixture

(d) change in colour of the product

Q. (a) What is meant by chemical reaction? Explain with the help of an example.
(b) Give one example each of a chemical reaction characterised by:
(i) evolution of a gas
(ii) change in colour
(iii) formation of a precipitate
(iv) change in temperature
(v) change in state.

Q. Give one example each of a chemical reaction characterised by:
(a) evolution of a gas
(b) formation of a precipitate
(c) change in temperature
​Write equations of the reactions which take place in each case.

Q.

Question 3

A chemical change may involve
(a) change in colour only
(b) change in temperature only
(c) evolution of gas only
(d) All of the these

Q. The chemical reaction between quicklime and water is characterised by:

Q.

Which of the following observations helps to determine whether a chemical reaction has taken place or not?

(i) Change in state.

(ii) Change in colour.

(iii) Change in shape

(iv) Evolution of gas.

(v) Change in temperature.