Question

Which of the following pairs consists of only network solid?
A.$Si{{O}_{2}},C{{O}_{2}}$
B. Graphite, $S{{O}_{2}}$
C.${{P}_{4}}{{O}_{10}},{{P}_{4}}{{O}_{6}}$
D. Diamond, $Si{{O}_{2}}$

Answer 1

Hint: Crystalline solids are compounds having a definite geometry. Crystalline solids are classified into various types like, metallic, ionic, molecular, and covalent solids. Covalent solids are also called network solids. They consist of covalent bonds between them.

Complete answer:
Network solids are the other name of covalent solids. Covalent solids are the type of crystalline solids that have atoms bonded together by covalent bonding forces. Covalent bond is the bond formed by the sharing of electron pairs, each atom shares an electron pair with its neighboring atom to complete their octet or noble gas configuration. They are called network solids as they are bonded in a continuous network throughout the substance. Individual and small molecules are not found in the crystal of such solids, and so these types of solids are considered as a whole macromolecule.
The pair among the given pairs that has only network solid is, Diamond, $Si{{O}_{2}}$. Diamond consist of a continuous carbon chain network bonded by covalent bonds, while $Si{{O}_{2}}$ is a quartz molecule, having covalent bonds between silicon and carbon due to low difference in their electronegativities, they form covalent bonds.
While other pairs has molecular solids (${{P}_{4}}{{O}_{10}},{{P}_{4}}{{O}_{6}}$,$S{{O}_{2}}$, and $C{{O}_{2}}$)

Hence, Diamond, $Si{{O}_{2}}$is a pair having only network solids, so option D is correct.

Note:
Network solids contain most of the hard substances which are insulators. Diamond is the hardest substance. Graphite also comes under network solid, but it is not a crystalline solid, it is an amorphous solid. These solids have a very high melting point. Molecular solids are those that consist of polar, non – polar molecules, or hydrogen bonding.