Question

When a metal rod is heated it expands because

• A. The size of its atoms increases
• B. The distance among its atoms increases
• C. Atmospheric air rushes into it
• D. The actual cause is still unknown

Answer 1

The correct option is B The distance among its atoms increases

When metal rod is heated it expands because as the temperature increases the atoms starts to vibrate. This vibration of atoms leads to the separation of atoms inside the metals. This separation is not enough to break the bonds between atoms but make them slightly apart. This is known as thermal expansion.

Hence, option B is correct answer.