How many grams of $Cu(NO_3)_2$ are needed to obtain $1 \ g$ of copper? $($ Atomic mass: $Cu = 63.5, N = 14, O = 16$ $)$

Given that $N_{2(g)} + 3 H_{2(g)} \longrightarrow 2 NH_{3(g)}$; $\Delta_r H^{\circ} = -92 \ kJ$,the standard molar enthalpy of formation in $kJ \ mol^{-1}$ of $NH_{3(g)}$ is

$300 \ mL$ of a gaseous hydrocarbon when burnt in excess of $O_2$ gave $2.4 \ L$ of $CO_2$ and $2.7 \ L$ of water vapour under same conditions. The molecular formula of the hydrocarbon is:

When a hydrocarbon $A$ undergoes combustion in the presence of air,it requires $9.5$ equivalents of oxygen and produces $3$ equivalents of water. What is the molecular formula of $A$?

What is the volume (in litres) of oxygen required at $STP$ to completely convert $1.5 \ mol$ of sulphur into sulphur dioxide?

Amount of oxygen required for combustion of $1 \, kg$ of a mixture of butane and isobutane is ............. $kg$.