The density of $$3 \mathrm{M}$$ solution of $$\mathrm{NaCl}$$ is $$1.0 \mathrm{~g} \mathrm{~mL}^{-1}$$. Molality of the solution is ____________ $$\times 10^{-2} \mathrm{~m}$$. (Nearest integer).

Given: Molar mass of $$\mathrm{Na}$$ and $$\mathrm{Cl}$$ is $$23$$ and $$35.5 \mathrm{~g} \mathrm{~mol}^{-1}$$ respectively.

Assume carbon burns according to the following equation :

$2 \mathrm{C}_{(\mathrm{s})}+\mathrm{O}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{CO}(\mathrm{g})$

when $12 \mathrm{~g}$ carbon is burnt in $48 \mathrm{~g}$ of oxygen, the volume of carbon monoxide produced is ___________ $\times 10^{-1} \mathrm{~L}$ at STP [nearest integer]

[Given: Assume $\mathrm{CO}$ as ideal gas, Mass of $\mathrm{C}$ is $12 \mathrm{~g} \mathrm{~mol}^{-1}$, Mass of $\mathrm{O}$ is $16 \mathrm{~g} \mathrm{~mol}^{-1}$ and molar volume of an ideal gas at STP is $22.7 \mathrm{~L} \mathrm{~mol}^{-1}$ ]

A sample of a metal oxide has formula $\mathrm{M}_{0.83} \mathrm{O}_{1.00}$. The metal $\mathrm{M}$ can exist in two oxidation states $+2$ and $+3$.

In the sample of $\mathrm{M}_{0.83} \mathrm{O}_{1.00}$, the percentage of metal ions existing in $+2$ oxidation state is __________ $\%$. (nearest integer)

Zinc reacts with hydrochloric acid to give hydrogen and zinc chloride. The volume of hydrogen gas produced at STP from the reaction of $$11.5 \mathrm{~g}$$ of zinc with excess $$\mathrm{HCl}$$ is __________ L (Nearest integer)

(Given : Molar mass of $$\mathrm{Zn}$$ is $$65.4 \mathrm{~g} \mathrm{~mol}^{-1}$$ and Molar volume of $$\mathrm{H}_{2}$$ at $$\mathrm{STP}=22.7 \mathrm{~L}$$ )