$FeSO_4 \cdot 7H_2O$ (Green Vitriol) salt on thermal decomposition does not produce

The transition metal ions responsible for colour in ruby and emerald are,respectively:

Which metal oxide is used to make blue glass?

The oxidation states of transition metal atoms in $K_{2}Cr_{2}O_{7}$,$KMnO_{4}$ and $K_{2}FeO_{4}$,respectively,are $x$,$y$ and $z$. The sum of $x$,$y$ and $z$ is

Zinc forms two important alloys,$(i)$ Brass and $(ii)$ German silver. Metals present in them mainly are

$I$. $4FeCr_2O_4 + 16NaOH + 7O_2 \rightarrow 8Na_2CrO_4 + 2Fe_2O_3 + 8H_2O$ (where $A = Na_2CrO_4$)
$II$. $2Na_2CrO_4 + H_2SO_4 \rightarrow Na_2Cr_2O_7 + Na_2SO_4 + H_2O$ (where $B = H_2SO_4$)
Compounds $(A)$ and $(B)$ are :