Green vitriol is . . . .

Match the following compounds in Column-$I$ with their products of heating effect in Column-$II$:

Column-$I$ (Compound)	Column-$II$ (Products of heating effect)
$a$. $LiNO_3$	$P$. Metal oxide
$b$. $FeSO_4 \cdot 7H_2O$	$Q$. Paramagnetic gas
$c$. $NaHCO_3$	$R$. Acidic gas
$d$. $BeCO_3$	$S$. Evolved gas has same number of $\sigma$ and $\pi$ bonds

The correct formula of hypo is

An aqueous solution of a colourless metal sulphate $M$ gives a white precipitate with $NaOH$. This precipitate is soluble in excess of $NaOH$. On passing $H_2S$ through this solution,a white precipitate is formed. The metal $M$ in the salt is:

Match List-$I$ with List-$II$.

List-$I$	List-$II$
$A$. Chlorophyll	$I$. $Na_2CO_3$
$B$. Soda ash	$II$. $CaSO_4$
$C$. Dentistry,Ornamental work	$III$. $Mg^{2+}$
$D$. Used in white washing	$IV$. $Ca(OH)_2$

Choose the correct answer from the options given below:

$A$ mixture of sodium oxide and calcium oxide is dissolved in water and saturated with excess carbon dioxide gas. The resulting solution is ...... It contains ......... :