Question

The increasing order of atomic radii of the following Group 13 elements is:

• A. $Al<In<Ga<Tl$
• B. $Ga<Al<In<Tl$
• C. $Al<Ga<In<Tl$
• D. $Al<Ga<T1<In$

Answer 1

The correct option is B $Ga<Al<In<Tl$

The increasing order of atomic radius of group 13 elements is: $Ga<Al<In<Tl$.
Due to the poor shielding of d-electrons in $Ga$, its radius is lesser than that of $Al$.