Question

Number of unpaired electrons in $\left[V\right(H_{2}O{)}_6{]}^{3+}$ is :

• A. 2
• B. 3
• C. 4
• D. 5

Answer 1

The correct option is A 2

Since water does not have any charge, V has a charge of +3 on it.

Usually, the 4s electrons are lower energy, but sometimes this isn't the case, leading to the occasional exception to Aufbau (not a rule, just a general principle).
For V, the neutral atom would have 2 4s and 3 3d electrons.

$V^{3+}$ has 3 electrons stripped from the V neutral atom. Leaving 2 electrons in 4s and removing the 3 3d electrons leave the ion in the lowest (and most stable) possible energy state.

Hence, the correct option is A.