Chemistry Liquids SZABMU 2023
PMDC Verified Question 20 of 73
Which of the following molecules are soft and have weak intermolecular forces?
A
\( \text{H}_2\text{O} \)
B
\( \text{I}_2 \)
C
Sugar
D
Graphite
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: \( \text{I}_2 \)
Concept:

Solids can be categorized by their internal bonding: molecular solids (weak forces, soft), network covalent solids (strong bonds, hard), and ionic/hydrogen bonded solids (crystalline, brittle).

Formula:

Not applicable.

Solution:

  • Iodine (\( \text{I}_2 \)) is a perfectly non-polar diatomic molecule. It crystallizes entirely via weak London dispersion forces. As a result, iodine crystals are very soft and readily sublime at low temperatures.


  • Ice (\( \text{H}_2\text{O} \)) is held by strong, rigid hydrogen bonds.


  • Sugar molecules form massive interlocked networks of strong hydrogen bonds, making them relatively hard crystalline solids.


  • Graphite is a giant covalent network solid (macromolecule) with extremely strong internal carbon-carbon covalent bonds, even though sliding layers exist.


Why other options are incorrect:

Only non-polar \( \text{I}_2 \) genuinely fits the textbook definition of a "soft solid with weak intermolecular forces" among the choices provided.

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