Question

The purification method based on the following physical transformation is: \[ {Solid} \xrightarrow{{Heat}} {Vapour} \xrightarrow{{Cool}} {Solid} \]

• A. Distillation
• B. Sublimation
• C. Crystallization
• D. Extraction

Hint:

Sublimation is a useful technique for purifying solids that can transition directly from the solid phase to the gas phase without passing through the liquid phase.

Answer 1

The Correct Option is B

The given physical transformation describes a purification method where a solid is converted to vapor through the application of heat and then back to solid upon cooling. The process involving this sequence of phase changes is known as sublimation.

Explanation: Sublimation is a technique used to purify substances that can transition from solid to vapor without passing through a liquid phase. When the solid substance is heated, it turns into vapor. Upon cooling, this vapor directly condenses back into a solid form. This method is effective for separating sublimable compounds from non-sublimable impurities.

The correct answer is Sublimation.

Answer 2

Step 1: Understand the transformation.
The given transformation is:
\[ \text{Solid} \xrightarrow{\text{Heat}} \text{Vapour} \xrightarrow{\text{Cool}} \text{Solid} \]
This indicates that the substance directly changes from solid to vapour upon heating and from vapour back to solid upon cooling, without passing through the liquid state.

Step 2: Identify the physical process.
The process in which a solid directly converts into vapour upon heating and the vapour condenses back to solid on cooling is called sublimation.
This method is commonly used for purifying substances that sublime, such as iodine, camphor, naphthalene, and ammonium chloride.

Step 3: Final Answer.
\[ \boxed{\text{Sublimation}} \]