Question

Which of the following elements has the largest atomic size?

• A. B
• B. C
• C. O
• D. Al

Answer 1

The correct option is D Al

The atomic size decreases on moving left to right across the period and increases on moving down the group. The elements B, C and O are present in the second period and belong to groups 13, 14 and 15 respectively while Al belongs to the third period and group 13. Therefore, the atomic size increases in the order O < C < B < Al.
Hence, the correct answer is option (d).