Which of the following solids are also known as giant molecules?

The correct answer is option 4. Covalent Solids.

The term "giant molecules" typically refers to solids that are composed of large molecules or networks of atoms held together by covalent bonds. These solids often have extremely high melting points and are characterized by strong bonds between the atoms or molecules.

1. Molecular Solids:

Molecular solids are composed of individual molecules held together by intermolecular forces (such as London dispersion forces, dipole-dipole interactions, or hydrogen bonding). They do not form extensive networks of covalent bonds, so they are not typically referred to as giant molecules.

2. Ionic Solids:

Ionic solids are composed of ions held together by ionic bonds. While they can form large crystal lattices, they are not typically referred to as giant molecules because they do not consist of covalently bonded molecules or networks.

3. Metallic Solids:

Metallic solids are composed of metal atoms held together by metallic bonds, where delocalized electrons move freely between metal atoms. They do not consist of large molecules or networks of covalently bonded atoms, so they are not considered giant molecules.

4. Covalent Solids:

Covalent solids, also known as network solids, are composed of atoms bonded together by strong covalent bonds to form a continuous network. These solids have large, three-dimensional structures, often with repeating units extending in all three dimensions. Examples include diamond (carbon atoms) and quartz (silicon dioxide). Because they consist of extensive networks of covalently bonded atoms, covalent solids are often referred to as giant molecules.

The correct answer is 4. Covalent Solids.

Covalent solids, also known as network solids, are considered giant molecules because they consist of large networks of atoms held together by strong covalent bonds. Examples include diamond, graphite, and silicon dioxide.