Question 19

Simultaneously in solid, liquid, and gas phases.

At the triple point of a substance, it exists simultaneously in solid, liquid, and gas phases. This unique condition occurs at a specific temperature and pressure that allows all three phases to coexist in thermodynamic equilibrium.

A) Simultaneously in solid, liquid, and gas phases.

This option is correct as it accurately describes the triple point, where a substance can be found in all three phases concurrently. The definition of the triple point is grounded in the principles of phase equilibrium, making this answer essential for understanding the behavior of substances under specific conditions.

B) As soil with gas and solid trapped in liquid.

This option is incorrect because it misrepresents the concept of the triple point by introducing unrelated components such as soil. The triple point specifically refers to a substance existing in its pure phases (solid, liquid, and gas) rather than a mixture with soil or any other material.

C) As a gel with solid and liquid trapped in gas.

This option is also incorrect. A gel is a colloidal state and does not represent a phase equilibrium among solid, liquid, and gas. The triple point concept does not involve gels or mixtures but strictly pertains to the coexistence of pure phases of a single substance.

D) Simultaneously in solid, gel, and plasma phases.

This option is incorrect as it includes gel and plasma, which do not pertain to the definition of the triple point. The phases relevant to the triple point are solid, liquid, and gas, making this answer inconsistent with the established scientific understanding.

Conclusion

The correct answer, A, is definitive because it accurately captures the essence of the triple point, where a substance exists in solid, liquid, and gas phases at equilibrium. All other options fail to reflect the correct phases involved, instead introducing irrelevant or incorrect states that do not align with the scientific principles of phase transitions.