Select the incorrect order.

Which of the following pairs of atomic numbers represents elements belonging to the $s$-block?

Match the following compounds (Column-$I$) with their uses (Column-$II$):

Column-$I$	Column-$II$
$I. Ca(OH)_2$	$A$. Casts of statues
$II. NaCl$	$B$. White wash
$III. CaSO_4 \cdot \frac{1}{2}H_2O$	$C$. Antacid
$IV. CaCO_3$	$D$. Washing soda preparation

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:

Identify the incorrect order against the property given in brackets.

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