CHEMICAL REACTIONS AND EQUATIONS – Part 1 (NCERT Questions)

Q1.  A solution of a substance ‘X’ is used for white washing.   (1). Name the substance ‘X’ and write its formula.   (2). Write the reaction of the substance ‘X’ named in (1) above with water.

Ans(1). Substance ‘X’ is CaO (Calcium oxide or quick lime).

Ans(2). Reaction of the substance ‘X’ is as follows:

CaO + H2O + Ca(OH)2

In the above example,

Calcium oxide reacts with water.

The product we get is Calcium hydroxide.

Q2. Why is the amount of gas collected in one of the test tubes in Activity 1.7 double the amount collected in the other? Name the gas.

Ans. In the Activity 1.7 the process of electrolysis of water is being performed.

This process of electrolysis gives two molecules of hydrogen (H2) at one electrode and one molecule of oxygen (O2) at the other electrode.

2H2O = 2H2 + O2

So, in electrolysis of water

    -  2 molecules of hydrogen are collected at electrode-1.

    - 1 molecule of oxygen is collected at electrode-2.

Thus, molecules collected at electrode-1 is double than that of electrode-2.

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