Which one of the following metallic hydroxides does not dissolve in sodium hydroxide solution?

Match Column-$I$ with Column-$II$ :

Column-$I$	Column-$II$
$(a)$ $NaOH$	$(p)$ Silvine
$(b)$ $Na_2CO_3$	$(q)$ As cooling agent in nuclear reactor
$(c)$ Liquid $Na$	$(r)$ Detergent soap
$(d)$ Potassium	$(s)$ In purification of Bauxite

Slow acting nitrogenous fertilizer among the following is

The two major constituents of Portland cement are

$A$ white solid '$A$' on heating produces a gas that turns lime water milky,and the remaining solid residue is yellow when hot but turns white on cooling. The solid '$A$' is:

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

column-$I$	column-$II$
$a$. $Ra$	$p$. Aeroplane industry
$b$. $K$	$q$. Down cell
$c$. $Li$	$r$. Photo electric cell
$d$. $Na$	$s$. Radioactive