Question

Solids expand the least and gases expand the most on being heated.
A. True
B. False

Answer 1

To determine whether the given statement is true or false, we need to understand the concept of thermal expansion of solid, liquid and gas. We know that all three states of matter solid, liquid and gas expand when they are heated. During this heating, the atoms themselves do not expand, however the volume they take up does expand.

Complete answer:
We will discuss the changes in all three matters that occur when they are heated.First, considering solid, it is observed that when a solid is heated, its atoms vibrate faster about their fixed points. So, the relative increase in the size of solids when heated is small. For example, metal railway tracks have small gaps so that when the sun heats them, the tracks expand into these gaps and do not buckle.

Also, l expand for the same reason, however they expand more than solids because the bonds between separate molecules are usually less tight. This is the concept used in the liquid-in-glass thermometers. An increase in temperature results in the expansion of the mercury which means it rises up the glass.

Finally, molecules within gases are further apart and weakly attracted to each other. Heat causes the molecules to move faster. Here, heat energy is converted to kinetic energy which means that the volume of a gas increases more than the volume of a solid or liquid.Thus, we can say that the given statement is true.

Hence, option A is the right answer.

Note: We can say that the expansion of a substance when heated is dependent on the strength of their molecular bond. The higher the attraction between the molecules, the higher will be its expansion. As this attraction is the most in solids and the least in gases, solids expand the least and gases expand the most on being heated.