Question

Which of the following is/are pseudo solids?
$I.$ $KCl$
$II.$ Barium chloride dihydrate
$III.$ Rubber
$IV.$ Solid cake left after distillation of coal tar

• A. $I,III$
• B. $II,III$
• C. $III,IV$
• D. only $III$

Answer 1

Answer: (C)

As we know, the solids are most stable in crystalline form. However, if a solid is formed rapidly, its atoms or molecules do not have time to align themselves and may become locked in positions other than those of a regular crystal. Such solids are called as pseudo solids. Hence, rubber and solid cake left after distillation of coal tar are examples of pseudo solids.
$KCl\&BaCl_{2}\cdot 2H_{2}O$ are ionic solids and not pseudo solids.