Which of the following is a molecular solid?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → I2
In a molecular solid the constituent particles are molecules held by weak intermolecular forces. Solid iodine is made of \( \ce{I2} \) molecules held by weak dispersion (London) forces, so it is a non-polar molecular solid: soft, a non-conductor, and it sublimes easily.
Why the other options are incorrect
Option (1) ZnS — Incorrect. It is an ionic solid built of \( \ce{Zn^{2+}} \) and S2– ions held by electrostatic forces.
Option (2) Diamond — Incorrect. It is a covalent (network) solid in which every carbon is joined to four others by covalent bonds throughout the crystal.
Option (3) SiC — Incorrect. Silicon carbide (carborundum) is also a covalent network solid, very hard with a high melting point.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Molecular Solids – “Molecules are the constituent particles of molecular solids. These are further sub divided into the following categories:
(i) Non polar Molecular Solids: They comprise of either atoms, for example, argon and helium or the molecules formed by non polar covalent bonds for example H2, Cl2 and I2. In these solids, the atoms or molecules are held by weak dispersion forces or London forces about which you have learnt in Class XI.”