Question

The melting points of most of the solid substances increase with an increase of pressure acting on them. However, ice melts at a temperature lower than its usual melting point, when the pressure increases. This is because :

• A. ice is less denser than water
• B. pressure generates heat
• C. the bounds break under pressure
• D. ice is not a true solid

Answer 1

Answer: (A)

ice is less denser than water

The ice melts at a temperature lower than its usual melting point, when the pressure increases. This is because ice is less denser than water.When water freezes, the molecules arrange themselves in a hexagonal lattice which maximizes this stability. This hexagonal structure is the reason that snowflakes have six sides. The lattice is also less dense than the random arrangement in liquid water. Increasing the pressure on ice causes it to melt.
$V_{ice}\to V_{water}$ and thus, increase in pressure favours forward reaction.