One mole of magnesium nitride on the reaction with an excess of water gives

$A$ $10 \ g$ effervescent tablet containing sodium bicarbonate $(NaHCO_3)$ and oxalic acid $(H_2C_2O_4)$ releases $0.25 \ L$ of $CO_2$ at $T = 298.15 \ K$ and $p = 1 \ bar$. If the molar volume of $CO_2$ is $25.0 \ L \ mol^{-1}$ under these conditions,what is the percentage by mass of sodium bicarbonate in each tablet? [Molar mass of $NaHCO_3 = 84 \ g \ mol^{-1}$,Molar mass of $H_2C_2O_4 = 90 \ g \ mol^{-1}$]

What volume of ammonia is required to react with $250 \ mL$ of oxygen by following the reaction at same conditions?
$4NH_3(g) + 5O_2(g) \to 4NO(g) + 6H_2O(g)$

How many kilograms of $CaCO_3$ must be heated to obtain $56$ kilograms of $CaO$? [Atomic masses: $Ca = 40, C = 12, O = 16$]

Equal masses in grams of $H_2$, $N_2$, $Cl_2$, and $O_2$ are enclosed in cylinders separately. If these gases expand isothermally and reversibly by $10 \ dm^3$ at $300 \ K$, the work done by the gas is maximum for:

At $300 \ K$ and $1 \ \text{atm}$ pressure,$10 \ mL$ of a hydrocarbon required $55 \ mL$ of $O_2$ for complete combustion,and $40 \ mL$ of $CO_2$ is formed. The formula of the hydrocarbon is