Air contains $23\%$ oxygen and $77\%$ nitrogen by weight. What is the percentage by volume of $O_2$?

$0.092 \ g$ of a compound with the molecular formula $C_3H_8O_3$ on reaction with an excess of $CH_3MgI$ gives $67.00 \ mL$ of methane at $STP$. The number of active hydrogen atoms present in a molecule of the compound is

The ammonia $(NH_{3})$ released on quantitative reaction of $0.6 \ g$ urea $(NH_{2}CONH_{2})$ with sodium hydroxide $(NaOH)$ can be neutralized by

$0.53 \ g$ of $Na_2CO_3$ has been dissolved in $100 \ mL$ of a sodium carbonate solution. The normality of the solution will be

To obtain the maximum mass of $NO_2$ from a given mass of a mixture of $NH_3$ and $O_2$,the ratio of the mass of $NH_3$ to $O_2$ should be based on the reaction: $NH_3 + O_2 \longrightarrow NO_2 + H_2O$

$A$ given initial mass of $KClO_3$ on $50\%$ decomposition produces $67.2 \ L$ of oxygen gas at $0 \ ^\circ C$ and $1 \ atm$. The other product of decomposition is $KCl$. The initial mass of $KClO_3$ (in $g$) taken is: