What volume (in $mL$) of gaseous $NH_3$ at $N.T.P.$ is required to be passed into $30 \, mL$ of $1 \, N \, H_2SO_4$ solution to reduce the acid strength of this solution to $0.2 \, N$?

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

Excess of $NaOH\, (aq)$ was added to $100\, mL$ of $FeCl_3\, (aq)$ resulting in $2.14\, g$ of $Fe(OH)_3$. The molarity of $FeCl_3\, (aq)$ is (Given molar mass of $Fe=56\, g\, mol^{-1}$ and molar mass of $Cl=35.5\, g\, mol^{-1}$) (in $, M$)

How many moles of ethene are required to prepare $6.0 \ g$ of ethane by the hydrogenation process (in $mole$)?

$100 \ mL$ of $PH_3$ when completely decomposed produces phosphorus and hydrogen. The change in volume of the gas is
$PH_{3(g)} \longrightarrow P_{(s)} + \frac{3}{2} H_{2(g)}$

The moles of methane required to produce $81 \ g$ of water after complete combustion is $.... \times 10^{-2} \ mol.$ [nearest integer]