The gas released when baking soda is mixed with vinegar is

$CaCO_{3(s)} + 2 HCl_{(aq)} \rightarrow CaCl_{2(aq)} + CO_{2(g)} + H_2O_{(l)}$
Consider the above reaction,what mass of $CaCl_2$ will be formed if $250 \ mL$ of $0.76 \ M \ HCl$ reacts with $1000 \ g$ of $CaCO_3$ (in $g$)?
(Given: Molar mass of $Ca, C, O, H$ and $Cl$ are $40, 12, 16, 1$ and $35.5 \ g \ mol^{-1}$,respectively)

$1.0 \ g$ of $Mg$ is burnt with $0.28 \ g$ of $O_2$ in a closed vessel. Which reactant is left in excess and how much?

If the heat of combustion of methane is $-100 \ kJ/mol$,then calculate the heat evolved when $32 \ g$ of methane reacts with $32 \ g$ of oxygen. (in $kJ$)

$KMnO_4$ reacts with $KI$ in basic medium to form $I_2$ and $MnO_2$. When $250 \ mL$ of $0.1 \ M \ KI$ solution is mixed with $250 \ mL$ of $0.02 \ M \ KMnO_4$ in basic medium, what is the number of moles of $I_2$ formed?

In the given reaction,$X + Y + 3 Z \rightleftharpoons XYZ_3$. If one mole of each of $X$ and $Y$ with $0.05 \ mol$ of $Z$ reacts to form the compound $XYZ_3$,calculate the yield of $XYZ_3$ in grams. (Given: Atomic masses of $X, Y$ and $Z$ are $10, 20$ and $30 \ amu$,respectively). (Nearest integer)