$150 \ g$ $CaCO_3$ sample was taken. On its complete decomposition $56 \ g$ $CaO$ is produced. The $\%$ purity of the sample is .............. $\%$

$A$ cylinder contains a mixture of $5 \ g$ of $N_2$ and $6 \ g$ of $Ar$ gases. If the total pressure of the mixture of the gases in the cylinder is $30 \ bar$,then the partial pressure of $N_2$ gas is (in $bar$)

The most abundant elements by mass in the body of a healthy human adult are: Oxygen $(61.4\%);$ Carbon $(22.9\%),$ Hydrogen $(10.0\%);$ and Nitrogen $(2.6\%).$ The weight which a $75 \ kg$ person would gain if all $^1H$ atoms are replaced by $^2H$ atoms is ....... $kg$.

$8 \ g$ of $H_2$ and $256 \ g$ of $HI$ are in a $4 \ L$ flask. Calculate their active mass. $(H = 1 \ g \ mol^{-1}, I = 127 \ g \ mol^{-1})$

If $500 \ mL$ of $CaCl_2$ solution contains $3.01 \times 10^{22}$ chloride ions,the molarity of the solution will be: (in $M$)

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: $NH_3 + O_2 \longrightarrow NO_2 + H_2O$