The electronic configuration of chromium is

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.

Which elements do you think would have been named by
$(i)$ Lawrence Berkeley Laboratory
$(ii)$ Seaborg's group?

$A$ transition element $X$ has a configuration $[Ar]3d^4$ in its $+3$ oxidation state. Its atomic number is

The second ionisation energy of the following elements follows the order

Which of the following elements has the highest number of unpaired electrons in its ground state?