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Chemistry Question 58 – JEE-MAIN 2025

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Given below are two statements : Statement (I) : The first ionisation enthalpy of group 14 elements is higher than the corresponding elements of group 13. Statement (II) : Melting points and boiling points of group 13 elements are in general much higher than those of corresponding elements of group 14. In the light of the above statements, choose the most appropriate answer from the options given below :

Recall the general trends of ionization enthalpy, melting points, and boiling points across a period and down a group in the periodic table.

Step 1: Analyze Statement I (Ionisation Enthalpy)✦ Active

Ionisation enthalpy generally increases across a period due to increasing effective nuclear charge and decreasing atomic size. Group 14 elements (ns2np2) have a higher effective nuclear charge and smaller atomic radii compared to corresponding Group 13 elements (ns2np1). Therefore, more energy is required to remove the first electron from Group 14 elements.

Thus, Statement I is correct.

Step 2: Analyze Statement II (Melting and Boiling Points)○ Expand

Group 14 elements (especially Carbon and Silicon) form strong covalent network structures, which require a large amount of energy to break, leading to exceptionally high melting and boiling points. Group 13 elements, while some like Boron are covalent, do not generally exhibit melting and boiling points 'much higher' than their corresponding Group 14 elements. For example, the melting point of Silicon (Group 14) is 1414∘C, which is higher than that of Aluminium (Group 13) at 660∘C. Carbon (diamond) has a much higher melting point than Boron.

Thus, Statement II is incorrect.

Step 3: Conclude based on both statements○ Expand

Since Statement I is correct and Statement II is incorrect, the most appropriate answer is option 3.

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