Chemistry Q53 – JEE-MAIN 2026

Home Chemistry Chemical BondingQuestion #224

The covalent radii of atoms A and B are

r_{A}

and

r_{B}

, respectively. The covalent bond length and total length of AB molecule are respectively

Clue 1 of 3: Conceptual Distinction

The question asks for two different length measurements for a diatomic molecule: the distance between the centers (nuclei) and the overall end-to-end distance of the molecule.

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Ninja Strategy•Definition Check

The covalent bond length is by definition $r_{A} + r_{B}$ , immediately eliminating options where the first term is different. The 'total length' must be a distinct, larger value, pointing to the correct choice.

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Step 1: Determine the Covalent Bond Length✦ Active

The covalent bond length of a molecule AB is the distance between the nuclei of atoms A and B. By definition, this is approximated as the sum of their individual covalent radii.

d_{A B} = r_{A} + r_{B}

Step 2: Determine the Total Length of the Molecule○ Expand

The 'total length' of the molecule refers to the end-to-end distance along the bond axis. This can be visualized as the distance from the outer edge of atom A, through both nuclei, to the outer edge of atom B. This is the sum of the radius of atom A, the internuclear distance (bond length), and the radius of atom B.

Total Length = r_{A} + d_{A B} + r_{B}

Substituting the expression for bond length from Step 1:

Total Length = r_{A} + (r_{A} + r_{B}) + r_{B} = 2 r_{A} + 2 r_{B} = 2 (r_{A} + r_{B})

Step 3: State the Final Answer○ Expand

The question asks for the covalent bond length and total length, respectively. Based on the calculations, the pair of values is $(r_{A} + r_{B})$ and $2 (r_{A} + r_{B})$ .

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Chemistry Question 53 – JEE-MAIN 2026

Clue 1 of 3: Conceptual Distinction

🧠 Full Solution Path