How many millilitres of $6.0 \ M$ hydrochloric acid should be used to prepare $150 \ mL$ of a solution which is $0.30 \ M$ in hydrogen ion?

If the mixture of $7 \ g$ of $N_2$ and $8 \ g$ of $Ar$ in a cylinder has a total pressure of $27 \ bar$,what is the partial pressure of $N_2$ (in $bar$)? (Atomic mass of $N = 14 \ g \ mol^{-1}$,$Ar = 40 \ g \ mol^{-1}$)

Calculate the approximate mass (in $g$) of $H_2S$ required for the following reaction when $15 \ L$ of oxygen at $STP$ reacts completely.
$2 H_2S_{(g)} + 3 O_{2(g)} \longrightarrow 2 SO_{2(g)} + 2 H_2O_{(g)}$
(molar mass of $H_2S = 34 \ g \ mol^{-1}$)

The decomposition of $H_2O_2$ produces $O_2$. If at a certain time,$48 \ g$ of $O_2$ is produced in $1 \ minute$,then the rate of formation of water at that time will be .......... $mol \ min^{-1}$.

$20 \ mL$ of methane is completely burnt using $50 \ mL$ of oxygen. The volume of the gas left after cooling to room temperature is (in $mL$)

What is the volume occupied by $2.5 \ mol$ of ammonia gas at $\text{STP}$ (in $dm^3$)?