An element having the electronic configuration $[Ar]3d^24s^2$ belongs to

Observe the following ions: $V^{2+}, Zn^{2+}, Cu^{2+}, Fe^{2+}, Fe^{3+}, Ti^{3+}, Sc^{3+}, Ti^{4+}, Ni^{3+}, Co^{3+}, Cu^+$. How many ions in the above list have zero magnetic moment?

The correct order of ionisation energy is:

The catalytic activity of transition elements is related to their

The number of unpaired electrons in $Mn^{3+}$ is

An element is in $M^{3+}$ form. Its electronic configuration is $[Ar]3d^1$. The ion is: