The transition metal ions responsible for colour in ruby and emerald are, respectively
$Co^{3+}$ and $Cr^{3+}$
$Co^{3+}$ and $Co^{3+}$
$Cr^{3+}$ and $Cr^{3+}$
$Cr^{3+}$ and $Co^{3+}$
$Zn$ and $Cd$ metals do not show variable valency because
Which metal is present in brass, bronze and German silver
Which one of the following metals will not reduce ${H_2}O$
Consider the hydrated ions of $Ti^{2+}, V^{2+}, Ti^{3+}$ and $Sc^{3+}$. The correct order of their spin-only magnetic moments is