The weight of $H_2C_2O_4 \cdot 2H_2O$ required to prepare $500 \ mL$ of $0.2 \ N$ solution is .......... $g$.

At $STP$, $7.5 \ g$ of a gas occupies $5.6 \ L$ of volume. The gas is:

What is the value of percent atom economy when an organic compound of formula weight $75 \ u$ is obtained from reactants having sum formula weight $225 \ u$?

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

$5.85 \, g$ of $NaCl$ is dissolved in $1 \, L$ of pure water. Calculate the total number of ions in $1 \, mL$ of this solution.

$20 \ g$ of iron pyrite,$FeS_2$,is roasted completely and the $SO_2$ gas produced is absorbed completely in $400 \ mL$ of $NaOH$ solution. If only $50\%$ of the $NaOH$ is used in the reaction,what was the molarity of the $NaOH$ solution?