The molarity of a $NaOH$ solution prepared by dissolving $4 \ g$ of it in $250 \ mL$ of water is: (in $M$)

What is the volume in $dm^3$ occupied by $3 \ mol$ of ammonia gas at $STP$?

How many grams of zinc are required to produce $224 \ mL$ of hydrogen from dilute $H_2SO_4$ at $STP$?

What fraction of $Fe$ exists as $Fe(III)$ in $Fe_{0.96}O$?
(Consider $Fe_{0.96}$ to be made up of $Fe(II)$ and $Fe(III)$ only)

To neutralize $25 \, mL$ of $0.25 \, M$ $Na_2CO_3$ solution,how much volume of $0.5 \, M$ $HCl$ is required? (Note: The reaction is $Na_2CO_3 + 2HCl \rightarrow 2NaCl + H_2O + CO_2$)

An aqueous solution of $4.5 \ g$ oxalic acid $(H_2C_2O_4)$ is made up to $250 \ mL$. Calculate the volume of $0.1 \ N$ $NaOH$ required to neutralize completely $20 \ mL$ of this solution.