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

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

When $17 \ g$ of $H_2A$ (dibasic acid) is completely neutralized with $100 \ mL$ of $1 \ M \ BOH$ (monoacidic base),the molecular weight of the acid is:

If isobutane and $n$-butane are present in a gas,then how much oxygen should be required for the complete combustion of $5 \ kg$ of this gas?

Galena (an ore) is partially oxidized by passing air through it at high temperature. After some time,the passage of air is stopped,but the heating is continued in a closed furnace such that the contents undergo self-reduction. The weight (in $kg$) of $Pb$ produced per $kg$ of $O_2$ consumed is $. . . . .$ (Atomic weights in $g \ mol^{-1}: O = 16, S = 32, Pb = 207$)

$25 \ mL$ of a solution of $Na_2CO_3$ having a specific gravity of $1.25$ required $32.9 \ mL$ of a solution of $HCl$ containing $109.5 \ g$ of the acid per litre for complete neutralization. Calculate the volume of $0.84 \ N$ $H_2SO_4$ that will be completely neutralized by $125 \ g$ of the $Na_2CO_3$ solution (in $mL$).