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 $Co^{3+}$
The melting point of $Zn$ is lower as compared to those of the other element of $3d$ series because
Assertion : Cuprous ion $(Cu^+)$ has unpaired electrons while cupric ion $(Cu^{2+})$ does not.
Reason : Cuprous ion $(Cu^+)$ is colourless whereas cupric ion $(Cu^{2+})$ is blue in the aqueous solution.
The atomic radii from $Cr$ to $Cu$ is almost identical because of
Which of the following electronic configuration would be associated with the highest magnetic moment?
Why $E^o$ values for $Mn,\,Ni$ and $Zn$ are more negative than expected ?