Question

The electronic configuration of a transition element '$X$' in $+3$ oxidation state is $\left[Ar\right]3d^5$. What is its atomic number?

• A. $24$
• B. $25$
• C. $26$
• D. $27$

Answer 1

The correct option is C $26$

$X^{3+}={\left[Ar\right]}^{18}3d^5=23$. As, $X^{3+}$ ion is formed by the loss of $3$ electrons from $X$, $X$ will have $26$ electrons.

Atomic number of $X=26$.