Question

arrange the following elements in increasing order their atomic radii
Na,Si, Mg,Li, P

Answer 1

Increasing order of atomic radii is:
P < Si < Li < Mg < Na
P, Si, Mg are in the same period and atomic radii decreases as we across the period, hence P is smaller than Si and Mg. Li is in period 1 and Mg is in 2 period hence Li is smaller than Mg.
Na is below Li down the group and before Mg in the same period hence is larger than both.