What volume of $CO_2$ at $STP$ is obtained by thermal decomposition of $20 \ g$ $KHCO_3$? [Atomic weight of $K = 39$]
$2KHCO_{3(s)} \to K_2CO_{3(s)} + CO_{2(g)} + H_2O_{(g)}$

The mass of sodium acetate $(CH_3COONa)$ required to prepare $250 \ mL$ of $0.35 \ M$ aqueous solution is . . . . . . $g$. (Molar mass of $CH_3COONa$ is $82.02 \ g \ mol^{-1}$)

$A$ $1.84 \, mg$ sample of polyhydric alcoholic compound '$X$' of molar mass $92.0 \, g/mol$ gave $1.344 \, mL$ of $H_2$ gas at $STP$. The number of alcoholic hydrogens present in compound '$X$' is $.....$

What mass of $95 \%$ pure $CaCO_3$ will be required to neutralise $50 \ mL$ of $0.5 \ M \ HCl$ solution according to the following reaction? (In $g$)
$CaCO_{3(s)} + 2HCl_{(aq)} \rightarrow CaCl_{2(aq)} + CO_{2(g)} + H_2O_{(l)}$
[Calculate up to the second decimal place]

How many moles of $H_2O_2$ are required for the decolorization of $1$ mole of $KMnO_4$?

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