In view of their low ionisation energies,the alkali metals are:

Match the following:

Compound	Uses
$1$. $CaCO_3$	$a$. In preparation of oils and fats
$2$. $NaOH$	$b$. As an antiseptic
$3$. $Ca(OH)_2$	$c$. As an antacid
$4$. $NaHCO_3$	$d$. For making bleaching powder

Which one of the following statements is not correct?

Arrange the following compounds in the increasing order of their thermal stability. Identify the correct sequence.
$I - K_2CO_3, II - MgCO_3, III - CaCO_3, IV - BeCO_3$

Match column $-I$ with column $-II$ :

Column $-I$	Column $-II$
$(a)$ Borax	$(p)$ $NaCl$
$(b)$ Carnallite	$(q)$ $KCl$
$(c)$ Rock salt	$(r)$ $KCl.MgCl_2.6H_2O$
$(d)$ Silvine	$(s)$ $Na_2B_4O_7.10H_2O$

Among $KO_2$,$AlO_2^-$,$BaO_2$,and $NO_2^+$,in which species is an unpaired electron present?