Question

Choose the correct answers.

• A. Ferric oxide
• B. Cuprous sulphate
• C. Ferrous chloride
• D. Mercuric oxide

Answer 1

Metals which exhibit more than one valency are named in the following way-
Name of the metal followed by 'ous' for the lower valency and 'ic' for higher valency.
Ferrous is $F{e}^{+2}$, Ferric is $F{e}^{+3}$, Mercuric is $H{g}^{+2}$ and Cuprous is $C{u}^{+}$.

Compound	Cation	Anion
$FeC{l}_2$	$F{e}^{+2}$	$C{l}^{-}$
$F{e}_2{O}_3$	$F{e}^{+3}$	$O^{-2}$
$C{u}_{2}S{O}_4$	$C{u}^{+}$	$S{O}_4^{-2}$
$HgO$	$H{g}^{+2}$	$O^{-2}$