Atomic radius of atoms in a period decreases with the increase in $Z_{\text{eff }}$. Which of the following is incorrect order of atomic radius?

As we move down a group, the atomic radius grows due to the filling of an extra shell with electrons. Nuclear charge rises by one unit over a period. As we proceed over the period, the radius contracts as a result of the electrons being drawn more tightly. Thus, the atomic radius always decreases from left to right. Hence, the incorrect order of atomic radius is $\begin{array}{r}\mathrm{Na}<\mathrm{Mg}<\mathrm{Al}<\mathrm{Si}\end{array}$.