According to the reaction,$Mg_{(s)} + 2HCl_{(aq)} \longrightarrow MgCl_{2_{(aq)}} + H_{2_{(g)}} \uparrow$,calculate the mass of $Mg$ required to liberate $4.48 \ dm^3$ of $H_2$ gas at $STP$. (Molar mass of $Mg = 24 \ g \ mol^{-1}$) (in $g$)

How many grams of residue is obtained by heating $2.76 \text{ g}$ of silver carbonate (in $\text{ g}$)? (Given: Molar mass of $C$, $O$ and $Ag$ are $12$, $16$ and $108 \text{ g mol}^{-1}$ respectively)

Which of the following has the same molar concentration as a $2N$ $HCl$ solution?

$X \ g$ of nitrobenzene on nitration gave $4.2 \ g$ of $m-$dinitrobenzene. $X = ............ \ g$. $(nearest \ integer)$ [Given: molar mass (in $g \ mol^{-1}$) $C: 12, H: 1, O: 16, N: 14$]

At $T \ K$,$3 \ moles$ of hydrogen and $1 \ mole$ of $N_2$ are allowed to react to form ammonia. When $1 \ mole$ of ammonia is formed,the total pressure in the vessel is $15 \ atm$. The partial pressure of $N_2$ in the vessel (in $atm$) is (in $.5$)

Sodium oxide reacts with water to produce sodium hydroxide. $20.0 \ g$ of sodium oxide is dissolved in $500 \ mL$ of water. Neglecting the change in volume,the concentration of the resulting $NaOH$ solution is $........ \times 10^{-1} \ M.$ (Nearest integer)
[Atomic mass $: Na=23.0, O=16.0, H=1.0]$