Question

Which of the following has the smallest atomic radii?

• A. B
• B. C
• C. Al
• D. Si

Answer 1

The correct option is B

C

Here, we have elements from group 13 and 14.
Do you remember the trend across a period and down the group?
Let's discuss it.
On moving from group 13 to group 14 within the same period, the effective nuclear charge increases and consequently the forces of attraction between the nucleus and the electrons increases, thereby decreasing the covalent radii.
And,
Atomic radii increase as we go down the group.
Therefore, $Al>B;Si>C$
but $C>B;Si<Al$
Therefore, Al is highest

C is smallest