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

Molecular crystalline solids consist of molecules held together by weak intermolecular forces, such as van der Waals forces or hydrogen bonds, rather than strong ionic, metallic, or covalent bonds [t1][t2]. Iodine (I2) is a classic example of a non-polar molecular solid that forms a crystalline lattice through weak van der Waals attractions [t1][t2]. Sulphur (S8) similarly exists as discrete molecules in a crystalline form [c3]. H2O (ice) is a polar molecular solid where molecules are held by hydrogen bonding [c1]. In contrast, Nickel, Zinc, and Manganese are metallic solids [t1]. Glass, cement, and rubber are largely amorphous or complex mixtures [t5]. While polymers like Polyethene and PVC contain large molecules, they are often classified as giant molecular substances or semi-crystalline polymers, and Graphite is a covalent network (giant covalent) solid [t1][t6].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.1.2 Non-metals > p. 39
2. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 7: Particulate Nature of Matter > Activity 7.3 : Let us find out > p. 103
3. [3] https://ftp.idu.ac.id/wp-content/uploads/ebook/tdg/TEKNOLOGI%20REKAYASA%20MATERIAL%20PERTAHANAN/Materials%20for%20engineering,%20by%20John%20Martin%20(z-lib.org).pdf