AIIMS2019Chemistry-Lanthanides

AIIMS 2019 Chemistry Lanthanide Contraction MCQ Question

Type: MCQ-conceptual-Medium-Class 12

The basic strength of hydroxides is La(OH)₃ > Lu(OH)₃. Due to lanthanide contraction, size of M³⁺ ions decrease and there is an increase in the covalent character of M⁻OH bond.

Correct Answer

Option C

Detailed Explanation

The basic strength of hydroxides in the lanthanide series is influenced by the decreasing size of M³⁺ ions due to lanthanide contraction, which leads to a greater covalent character in the M⁻OH bond. As the size of the M³⁺ ion decreases from La³⁺ to Lu³⁺, the ability of the ion to polarize the hydroxide ion (OH⁻) increases, resulting in stronger covalent interactions and thus a decrease in basicity. Other options are not relevant as they do not provide any alternative explanations or correct answers regarding the basic strength of hydroxides in this context.

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