The oxoanion which contains all equivalent $M-O$ bonds is:
$(I)$ $CrO_4^{2-}$
$(II)$ $MnO_4^-$
$(III)$ $Cr_2O_7^{2-}$

Thermal decomposition of a $Mn$ compound $(X)$ at $513 \ K$ results in compound $Y$,$MnO_2$ and a gaseous product. $MnO_2$ reacts with $NaCl$ and concentrated $H_2SO_4$ to give a pungent gas $Z$. Identify $X, Y$ and $Z$.

Which among the following statements is incorrect for interstitial compounds?
$1$. They are very hard and rigid
$2$. They have higher melting point than pure metal
$3$. They do not show conductivity
$4$. They are chemically inert

Complete the following reactions:
$(a)$ $4FeCr_2O_4 + 8Na_2CO_3 + 7O_2 \to 8Na_2CrO_4 + 2Fe_2O_3 + 8CO_2$
$(b)$ $2Na_2CrO_4 + 2H^+ \to Na_2Cr_2O_7 + 2Na^+ + H_2O$
Identify the species $X$ in both reactions.

$MnO^{-}_4$ is of intense pink colour,though $Mn$ is in $(+7)$ oxidation state,it is due to

Which product is formed by the reaction of an acidic solution of chromic acid with hydrogen peroxide?