The right option for the mass of $CO_2$ produced by heating $20 \ g$ of $20 \%$ pure limestone is $........ \ g$ (Atomic mass of $Ca = 40$) $[CaCO_3 \stackrel{1200 \ K}{\longrightarrow} CaO + CO_2]$

Calculate the amount of $NO_2$ required for producing $4$ moles of $HNO_3$ as per the chemical reaction,$3 NO_2 + H_2O \longrightarrow 2 HNO_3 + NO$. (in $g$)

For preparing a $0.1 \ N$ solution of a compound from its impure sample,where the percentage purity is known,the weight of the substance required will be:

$A$ $300 \ mL$ bottle of soft drink has $0.2 \ M$ $CO_2$ dissolved in it. Assuming $CO_2$ behaves as an ideal gas,the volume of the dissolved $CO_2$ at $STP$ is $...... \ mL$. (Nearest integer) Given: At $STP$,molar volume of an ideal gas is $22.7 \ L \ mol^{-1}$.

The mass of a mixture containing $NaCl$ and $NaBr$ is $4.0 \ g$. If $Na$ is $30 \%$ of the total mixture,the composition of $NaCl$ in the mixture is (in $\%$)

What is the volume occupied by $2 \ g$ of helium gas at $STP$ (in $dm^3$)? (molar mass of helium gas $= 4 \ g \ mol^{-1}$)