What is the actual volume occupied by water molecules present in $20 \ cm^3$ of water (in $cm^3$)?

$0.45 \ g$ of an organic compound on combustion gives $0.792 \ g$ of $CO_2$ and $0.324 \ g$ of $H_2O$. In the Kjeldahl method,$0.24 \ g$ of the same compound yields ammonia,which is absorbed in $50 \ mL$ of $0.25 \ N \ H_2SO_4$. The excess acid requires $77.0 \ mL$ of $0.25 \ N \ NaOH$ for neutralization. Determine the empirical formula of the compound. (Atomic masses: $C = 12, H = 1, O = 16, N = 14, S = 32$)

In which of the following reactions is no gas evolved on the product side? (Temperature is maintained below the boiling point of liquids formed)

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

When a standard solution of $NaOH$ is left in air for a few hours,

An inorganic compound first melts,then resolidifies,and then liberates a gas. It may be