Question

Which of the following is/are molecular solid(s)?

• A. Solid SO₂
• B. Diamond
• C. Iron (Fe)
• D. CaF₂

Answer 1

The correct option is A

Solid SO₂

To answer this question, first we need to know about the types of crystalline solids.

Molecular solids $\to$ In these solids, the constituent particles are molecules.

Metallic solids $\to$ In such solids, the constituent particles are orderly arranged positively charged metal ions (called kernels) surrounded by a sea of free electrons. These electrons are mobile and are evenly spread out throughout the crystal and flow throughout the metal crystal such as water in the sea. These are produced from metal atoms having low ionization energy and can easily lose their valence electrons to leave behind positively charged ions (kernels). Each metal atom contributes one or more electrons towards this sea of mobile electrons. Hence, it is called electrons sea model.

Ionic Solids $\to$ In ionic solids, the constituent particles are positive and negative ions. Such solids are formed by the three-dimensional arrangement of positive (cations) and negative (anions)( ions held by strong electrostatic (coulombic) force of attraction.

Covalent solid $\to$ In covalent solids, the constituent particles are non-metal atoms linked to the adjacent atoms by covalent bonds throughout the crystal. As a result, a network of covalent bond is formed. Hence, they form giant molecules.

So, here

Diamond $\to$ Giant 3-d network with covalent bonds between carbon.

So, covalent solid Iron (Fe) $\to$ Metallic solid

$Ca{F}_2$ $\to$ Ionic solid

Constituent particles are $C{a}^{2+}$ and $F^{-}$ ions

Solid $S{O}_2$ $\to$ molecular solid

Here the constituent particles are $S{O}_2$ molecules.