What products are formed when $1 \ mol$ of magnesium nitride is reacted with excess water?

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

$10 \ mL$ of an aqueous solution containing $222 \ mg$ of calcium chloride $(mol. wt. = 111)$ is diluted to $100 \ mL$. The concentration of chloride ion in the resulting solution is $..... \ mol/L$.

Ammonia on reaction with chlorine forms an explosive $NCl_3$. What is the mole ratio of $NH_3$ and $Cl_2$ required for this reaction?

One mole of calcium phosphide on reaction with excess of water gives

Calcium carbonate reacts with aqueous $HCl$ to give $CaCl_{2}$ and $CO_{2}$ according to the reaction,
$CaCO_{3(s)} + 2HCl_{(aq)} \rightarrow CaCl_{2(aq)} + CO_{2(g)} + H_{2}O_{(l)}$
What mass of $CaCO_{3}$ is required to react completely with $25 \ mL$ of $0.75 \ M$ $HCl$ (in $g$)?