Iron on reacting with carbon gives:

Which of the following imparts green colour to the glass?

The yellow colour solution of $Na_2CrO_4$ changes to orange-red on passing $CO_2$ gas due to the formation of $:-$

The amphoteric oxide among $V_2O_3$,$V_2O_4$,and $V_2O_5$ upon reaction with alkali leads to the formation of an oxide anion. The oxidation state of $V$ in the oxide anion is:

$A \xrightarrow{4 KOH, O_2} 2 B (Green) + 2 H_2O$
$3 B \xrightarrow{4 HCl} 2 C (Purple) + MnO_2 + 2 H_2O$
$3 C \xrightarrow{H_2O, KI} 2 A + 2 KOH + D$
In the above sequence of reactions,$A$ and $D$,respectively,are:

The most basic hydroxide among the following is