How much $MgO$ is produced from $1.2 \ g$ of $Mg$ (atomic mass $= 24$)?

Element $A$ reacts with oxygen to form a compound $A_2O_3$. If $0.359 \ g$ of $A$ reacts to form $0.559 \ g$ of the compound,the atomic mass of $A$ 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]

What will be the amount of $MgCl_2$ produced when $17 \ g$ of $HCl$ is reacted with an excess of $MgO$ in the following reaction?
$MgO + 2HCl \longrightarrow MgCl_2 + H_2O$

Match the following List-$I$ and List-$II$ at $STP$:

List-$I$	List-$II$
$A. 10 \ g \ CaCO_3 \xrightarrow{\Delta} \text{decomposition}$	$1. 0.224 \ L \ CO_2$
$B. 1.06 \ g \ Na_2CO_3 \xrightarrow{\text{Excess } HCl} \text{reaction}$	$2. 4.48 \ L \ CO_2$
$C. 2.4 \ g \ C \xrightarrow{\text{Excess } O_2} \text{combustion}$	$3. 0.448 \ L \ CO_2$
$D. 0.56 \ g \ CO \xrightarrow{\text{Excess } O_2} \text{combustion}$	$4. 2.24 \ L \ CO_2$
	$5. 22.4 \ L \ CO_2$

Three solutions of $HCl$ having normalities $12 \ N$,$6 \ N$,and $2 \ N$ are mixed to obtain a solution of $4 \ N$ normality. Which among the following volume ratios is incorrect for the above mixture?