Chemistry - Atomic Structure Question with Solution | TestHub

Atomic number (Z) increases as C (6) < N (7) < O (8), so O > N > C is correct.

Number of protons equals the atomic number; hence P (15) < S (16) < Cl (17) is correct.

The azimuthal quantum number has values s = 0, p = 1, d = 2, so s < p < d is correct.

The 1st, 2nd, and 3rd periods each contain 2 s-block elements, so option (D) is incorrect.

Answer: (A), (B) and (C)