Explanation:
(b) Quantity of \({H_2}{O_2} = 15\,ml\) and volume of \({H_2}{O_2} = 20\)
We know that \(20\) volume of \({H_2}{O_2}\) means \(1\, litre\) of this solution will give \(20\,litre\) of oxygen at \(N.T.P\).
Since, oxygen liberated from \(1000\,ml\) (\(1\, litre\)) of \({H_2}{O_2} = 20\,litre\),
therefore oxygen liberate from \(15\, ml\) of \({H_2}{O_2}\) \( = \frac{{20}}{{1000}} \times 15 = 0.3\,litre = 300\,ml\)
