Which property is comparatively insensitive to pressure changes under ordinary conditions?

Introduction / Context:
Thermophysical properties respond differently to changes in pressure. Distinguishing which properties are sensitive helps prioritize what needs accurate pressure control in processes like distillation, crystallization, and high-pressure materials handling.

Given Data / Assumptions:

• Ordinary pressure ranges (near 1 atm to a few tens of bar).
• Condensed phases (solids and liquids) are relatively incompressible.
• Boiling (vaporization) involves a large volume change, while melting involves a small one.

Concept / Approach:
By the Clausius–Clapeyron relation, dP/dT depends on ΔH/(T * ΔV). Vaporization entails a huge ΔV between liquid and vapor, making saturation temperature (boiling point) and heat of vaporization quite pressure sensitive. In contrast, melting involves small ΔV between solid and liquid for most substances, so melting point varies little with pressure, and the heat of fusion exhibits relatively weak pressure dependence in ordinary ranges.

Step-by-Step Solution:
Compare ΔV for vaporization (very large) with that for fusion (small).Large ΔV implies strong pressure sensitivity (boiling/ΔHvap).Small ΔV implies weak pressure sensitivity (melting point/ΔHfus).Therefore, properties in (b) and (c) are comparatively insensitive.

Verification / Alternative check:
Engineering data show boiling point curves shifting markedly with pressure, while melting points shift only slightly unless at extremely high pressures or for anomalous materials like water near special regions.

Why Other Options Are Wrong:
Heat of vaporization (a) varies significantly with pressure via saturation conditions.

Common Pitfalls:
Assuming absolute insensitivity; while the dependence is weak for melting-related quantities, it is not zero and can matter at very high pressures.

Final Answer:
Both (b) and (c)