K L Chugh Solutions for Chapter: Solid State, Exercise 1: Follow Up Problems

Why is glass regarded as an amorphous solid?

Classify each of the following solids as molecular, ionic, network (covalent), metallic or amorphous:

(i) ${\mathrm{I}}_2$     (ii) Tetraphosphorus decaoxide (${\mathrm{P}}_4{\mathrm{O}}_{10}$)     (iii) ${\mathrm{P}}_4$     (iv) ${\mathrm{S}}_8$    (v) Plastic

(vi) Brass   (vii) $\mathrm{SiC}$  (viii) Graphite  (ix) $\mathrm{Rb}$    (x) $\mathrm{Si}$   (xi) Ammonium phosphate

(xii) $\mathrm{LiBr}$    (xiii) Wax    (xiv) Ice     (xv) Solid ${\mathrm{CO}}_2$       (xvi) $\mathrm{Al}$      (xvii) Naphthalene

(xviii) $\mathrm{CsCl}$      (xix) Sugar      (xx) ${\mathrm{SiO}}_2$      (xxi) Glass

Why the window glass panes of the old buildings are thick at the bottom?

Some glass objects from ancient civilisations look milky instead of being transparent. Explain.

Ions of $\mathrm{NaF}$ and $\mathrm{MgO}$ all have the same number of electrons and internuclear distances are about the same ($235 \mathrm{pm}$ and $215 \mathrm{pm}$). Why then are the melting points of $\mathrm{NaF} (992°\mathrm{C})$ and $\mathrm{MgO} (2642°\mathrm{C})$ are so different?

Covalent bonding occurs in both molecular and covalent network solids. Why do these two kinds of solids differ so greatly in their hardness and melting point?

Sodium chloride crystals are harder than sodium metal. Why?

Why carborundum ($\mathrm{SiC}$) is very hard and used as an abrasive?