NEET Chemistry Question (2026) — Solution

Step-by-step solution

Atomic radius decreases across a period from left to right, so the atomic radius of Mg is greater than that of Al . For isoelectronic species, the ionic radius decreases with an increase in nuclear charge. Both Mg ^ 2+ and Al ^ 3+ have 10 electrons, but Al ^ 3+ has a higher nuclear charge (Z=13) compared to Mg ^ 2+ (Z=12), making Al ^ 3+ smaller than Mg ^ 2+ . Cations are always smaller than their respective parent atoms. Therefore, the overall decreasing order of size is Mg > Al > Mg ^ 2+ > Al ^ 3+ . The largest species is Mg and the smallest is Al ^ 3+ . Thus, statement (1) is incorrect. For atomic number 107, the IUPAC roots are un (1), nil (0), and sept (7), giving the name Unnilseptium. Statement (2) is correct. Lithium and Magnesium exhibit similar properties due to their comparable polarizing power (charge-to-size ratio), which is known as a diagonal relationship. Statement (3) is correct. In the complex [ AlCl ( H _2 O )_5]^ 2+ , let the oxidation state of Al be x. We have x + (-1) + 5(0) = +2 x = +3. The central metal atom is surrounded by 6 ligands (1 chloride and 5 water molecules), so its covalency is 6. Statement (4) is correct. Answer: The largest and the smallest species among Mg, Mg ^ 2+ , Al and Al ^ 3+ are Al and Mg ^ 2+ , respectively.