$A$ gas has a density of $2.68 \ g/L$ at $STP$. Identify the gas.

$25 \ mL$ of $0.1 \ N \ NaOH$ solution neutralises $12.5 \ mL$ of $HCl$ solution. The amount of water needed to convert $500 \ mL$ of such $HCl$ solution to $0.1 \ N$ is (in $mL$)

What is the approximate volume occupied by $22.4 \, L$ of water vapor at $STP$ when it is condensed into liquid water?

Identify the type of reaction for the following chemical equation:
$CuSO_4 + 2NaOH (excess) \longrightarrow Cu(OH)_2 \downarrow + Na_2SO_4$

The ratio of the number of water molecules in Mohr's salt and potash alum is $.... \times 10^{-1}$.

Which of the following is $NOT$ true for $1 \ g$ of Helium?