Concept:The freezing/melting point of a substance is the temperature at which its solid and liquid phases exist in dynamic equilibrium.
Formula:$$ \text{H}_2\text{O}_{(s)} \rightleftharpoons \text{H}_2\text{O}_{(l)} $$
Solution:- At exactly \( 0^\circ\text{C} \) (standard pressure), pure water reaches its freezing point.
- At this exact temperature threshold, heat added will melt the ice, and heat removed will freeze the water, but the temperature will remain \( 0^\circ\text{C} \) during the phase change.
- Because both phases are undergoing dynamic interchange, water will exist in both solid (ice) and liquid forms simultaneously.
Why other options are incorrect:Choosing only "Ice" or only "Liquid" ignores the principles of phase equilibrium during a transition state.
Quality & Fidelity Assurance:
Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.