Which one of the following sets of substances can exist as molecular crystalline solids?

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Q: 73 (NDA-II/2008)

Which one of the following sets of substances can exist as molecular crystalline solids?

question_subject: 

Science

question_exam: 

NDA-II

stats: 

0,10,31,9,8,14,10

keywords: 

{'molecular crystalline solids': [0, 0, 1, 0], 'substances': [0, 0, 1, 1], 'polyethene': [0, 0, 1, 0], 'graphite': [0, 0, 3, 9], 'glass': [0, 0, 1, 4], 'zinc': [1, 0, 0, 2], 'cement': [0, 0, 1, 4], 'polyvinyl chloride': [0, 1, 1, 4], 'manganese': [2, 0, 0, 1], 'rubber': [0, 0, 0, 1], 'sets': [4, 3, 5, 2], 'nickel': [1, 0, 0, 0], 'sulphur': [0, 0, 0, 2], 'iodine': [2, 1, 1, 1]}

The correct answer is option 4: Iodine, Sulphur, I2O

In molecular crystalline solids, the substances are held together by weak intermolecular forces. This results in the formation of a lattice structure composed of individual molecules.

Option 1, which includes Nickel, Zinc, and Manganese, is incorrect because these metals form metallic solids, where the atoms are strongly bonded together with delocalized electrons.

Option 2, which includes Glass, Cement, and Rubber, is incorrect because these materials are not composed of individual molecules. Glass is an amorphous solid, while cement and rubber are composed of large macromolecules or networks of atoms.

Option 3, which includes Polyethene, Polyvinyl Chloride, and Graphite, is incorrect because these substances are not molecular solids. Polyethene and Polyvinyl Chloride are polymers consisting of repeating units, while graphite is composed of layers of carbon atoms.

Therefore, the correct answer is option 4 because Iodine, Sulphur, and I2O are all molecular substances that can form molecular crystalline solids.