Statement-1: Sublimation is a purification technique that is used to separate those solid substances which change from solid to vapor state without passing through liquid state. Statement-2: If external atmospheric pressure is reduced, then boiling point of substance decreases.
Which of the following is correct?
Show Hint
Sublimation is used for purifying volatile substances, while changes in pressure can affect the boiling point of substances, which is particularly important in distillation and other purification techniques.
Statement-1 is correct but Statement-2 is incorrect.
Statement-1 is incorrect but Statement-2 is correct.
Show Solution
The Correct Option isA
Solution and Explanation
Let's evaluate both statements presented in the question to determine their correctness:
Statement-1: Sublimation is a purification technique that is used to separate those solid substances which change from solid to vapor state without passing through liquid state.
Sublimation is indeed a technique used to purify substances that transition directly from solid to gas, bypassing the liquid phase.
This process is useful for purifying compounds like iodine, dry ice (solid CO₂), and naphthalene, which have this characteristic property.
Therefore, Statement-1 is correct.
Statement-2: If external atmospheric pressure is reduced, then boiling point of substance decreases.
Boiling occurs when the vapor pressure of a liquid equals the external pressure acting on the liquid surface.
If the external atmospheric pressure is reduced, a liquid requires less energy (lower temperature) for its vapor pressure to reach the atmospheric pressure.
This phenomenon results in a decrease in the boiling point of the substance, as seen in high-altitude areas where water boils at temperatures lower than 100°C.
Therefore, Statement-2 is correct.
Based on the analysis above, both Statement-1 and Statement-2 are accurate. Thus, the correct answer is:
