Which compound on heating produces a coloured metal oxide finally?

$A$ pink colored salt on dry heating becomes blue in colour. The salt may contain:

For a good quality cement,the ratio of lime to the total of the oxides of $Si$,$Al$ and $Fe$ should be as close as to :

$A$ hydrated solid $X$ on heating initially gives a monohydrated compound $Y$. $Y$ upon heating above $373 \ K$ leads to an anhydrous white powder $Z$. $X$ and $Z$,respectively,are

Slow acting nitrogenous fertilizer among the following is

The pair$(s)$ of reagents that yield paramagnetic species is/are:
$A$. $Na$ and excess of $NH_3$
$B$. $K$ and excess of $O_2$
$C$. $Cu$ and dilute $HNO_3$
$D$. $O_2$ and $2-ethylanthraquinol$