At $STP$,$4.4 \ g$ of an unknown gas occupies a volume of $2.24 \ L$. What is the gas?

The $NaNO_3$ weighed out to make $50 \ mL$ of an aqueous solution containing $70.0 \ mg$ $Na^{+}$ per $mL$ is $...... \ g$.
(Rounded off to the nearest integer) [Given : Atomic weight in $g \ mol^{-1}$ - $Na : 23$; $N : 14$; $O : 16$]

What is the value of percent atom economy if the molar mass of reactants is $36 \ u$ and the mass of the desired product is $27 \ u$ (in $\%$)?

When excess silver nitrate is added to $5.850 \ g$ of sodium chloride,how many grams of silver chloride are produced?

What volume of a solution of hydrochloric acid containing $73 \ g$ of acid per litre would be sufficient for the exact neutralization of sodium hydroxide obtained by allowing $0.46 \ g$ metallic sodium to act upon water? $(Cl = 35.5, Na = 23.0, O = 16, H = 1)$

$A$ cylinder of gas is assumed to contain $11.2 \ kg$ of butane $(C_4H_{10})$. If a normal family needs $20000 \ kJ$ of energy per day,the cylinder will last: (Given that $\Delta H$ for combustion of butane is $-2658 \ kJ/mol$)....$days$