Question

Given below are two statements:
Statement (I): NaCl is added to the ice at \( 0^\circ C \), present in the ice cream box to prevent the melting of ice cream.
Statement (II): On addition of NaCl to ice at \( 0^\circ C \), there is a depression in freezing point.
In the light of the above statements, choose the correct answer from the options given below:

• A. Statement I is false but Statement II is true
• B. Both Statement I and Statement II are true
• C. Statement I is false but Statement II is true
• D. Statement I is true but Statement II is false

Hint:

Freezing point depression occurs when a solute (like NaCl) is added to a solvent (like water), causing the freezing point to lower. This is a colligative property that depends on the concentration of solute particles.

Answer 1

The Correct Option is B

- Statement (I): The addition of NaCl to ice helps lower the freezing point of water, preventing the ice from melting at \( 0^\circ C \) and thus allowing for the ice cream to stay frozen at lower temperatures. This statement is correct. 
- Statement (II): Adding NaCl to ice creates a phenomenon known as freezing point depression, which lowers the freezing point of water and ice. This is a well-known colligative property of solutions. Hence, this statement is also correct. 
Therefore, both statements are true.

Answer 2

Step 1: Understand the statements.
Statement (I): NaCl is added to the ice at \( 0^\circ C \), present in the ice cream box to prevent the melting of ice cream.
Statement (II): On addition of NaCl to ice at \( 0^\circ C \), there is a depression in freezing point.

Step 2: Analyze Statement (I).
When NaCl (common salt) is added to ice, it dissolves in the thin layer of water that is always present on the surface of the ice. This lowers the freezing point of the mixture, so the ice-water mixture can exist at a temperature below \( 0^\circ C \). This lower temperature helps to keep the ice cream from melting. Hence, Statement (I) is true.

Step 3: Analyze Statement (II).
Adding NaCl to ice causes a phenomenon known as freezing point depression. This is a colligative property where the addition of a non-volatile solute (NaCl) to a solvent (water) lowers the freezing point of the solvent. Therefore, the ice melts at a temperature lower than \( 0^\circ C \). Hence, Statement (II) is also true.

Step 4: Conclusion.
Both statements correctly describe the physical behavior of the ice-salt mixture. Statement (I) explains the practical application, and Statement (II) gives the theoretical reason behind it.

Final Answer:
Both Statement I and Statement II are true.
\[ \boxed{\text{Both Statement I and Statement II are true.}} \]