Concept:Bond length varies directly with atomic size and inversely with bond multiplicity.
Explanation:Bond length is the distance between the nuclei of two bonded atoms.
When the atoms are larger, their nuclei lie farther apart, so bond length increases.
Thus,
Bond length∝size of atom.
This is a direct proportionality.
Example:
H−F<H−Cl<H−Br<H−I, as atomic size increases down the group.
Bond multiplicity refers to single, double, or triple bonds.
Multiple bonds involve more shared electron pairs, which pull the nuclei closer.
Hence,
Bond length∝bond multiplicity1.
This is an inverse proportionality.
Example:
C−C>C=C>C≡C in bond length.
Answer:(I) direct, (II) inverse.
Therefore, the correct option is A.