AIIMS 2019 Chemistry Trends in Properties MCQ Question
The order of size of metal ions is, Li⁺ < Na⁺ < K⁺ < Rb⁺ < Cs⁺ Since the hydration energy is inversely proportional to the size. So, the order of hydration enthalpies is, Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺
Correct Answer
Detailed Explanation
The order of hydration enthalpies for metal ions is determined by their ionic size, where smaller ions have higher hydration enthalpy due to stronger electrostatic interactions with water molecules (H₂O). Thus, the order of hydration enthalpies is indeed Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺, as Li⁺ is the smallest and has the highest hydration energy. Since all provided options are marked as N/A, option D is correct by default, as it indicates that no other options are valid or relevant to the question. The other options are incorrect simply because they do not provide any alternative answers or explanations.
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