Chapter 11, Problem 11.16A

(a)

Interpretation Introduction

Interpretation:

All the phases of Ga should be identified in the phase diagram.

Concept introduction:

The solid phase is present up to 270 - 280 K at all pressure whereas liquid phase appears after 280 - 290 K. Now, the Vapor phase appears after 300 K below 1 atm pressure and vapor phase exist up to 1 atm pressure.

(b)

Interpretation Introduction

Interpretation:

Triple point should be identified in the phase diagram.

Concept introduction:

In a phase diagram, a triple point is the point at which all the three phases that is solid, liquid and vapor are in equilibrium with each other.

(c)

Interpretation Introduction

Interpretation:

Denser phase should be identified.

Concept introduction:

Pressure is inversely related to volume, it is represented as follows:

    $\text{P}=\text{nRT}/\text{V}$

With increase in pressure, the volume of the matter decreases whereas with decrease in pressure, the volume increases.
Similarly, density and volume also inversely proportional to each other as follows:

    $\text{d}=\text{m}/\text{V}$