Q. Among the following ions (hydrated), the colourless metal ion is
A) ${Cu}^{+}$
B) ${Cu}^{2 +}$
C) ${Fe}^{2 +}$
D) ${Mn}^{2 +}$
Explanation
(a)
Transitional metal ions having electronic configuration ($n$-1)$d^{0}\ or\ (n - 1)d^{10}$ are colourless while those have $(n - 1)d^{1 - 9}$ are coloured.
$Cu^{+}:\lbrack Ar\rbrack\ 3d^{10}\ :colourless$
$Cu^{2 +}:\lbrack Ar\rbrack\ 3d^{9}\ :coloured$
$Fe\ ^{2 +}:\lbrack Ar\rbrack\ 3d^{6}\ :coloured$
$Mn\ ^{2 +}:\lbrack Ar\rbrack\ 3d^{5}\ :coloured$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.