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

Both Statement I and Statement II are true

Both Statement I and Statement II are false

Statement I is true but Statement II is false

Statement I is false but Statement II is true

Solutions PYQ — JEE Main 2025 · 29 Jan · Shift 2 · Q3 with Solution

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Correct answer: C

Understand Statement (II) first

Statement (II): On addition of NaCl to ice at $0^\circ\text{C}$ , there is a depression in freezing point.

This is a standard colligative property.

When a non-volatile solute like NaCl is added to water/ice system, the freezing point of the solution becomes lower than that of pure water.

Mathematically, $\Delta T_f = iK_f m$ where:
- $i$ = van’t Hoff factor,
- $K_f$ = cryoscopic constant,
- $m$ = molality.
Since NaCl dissociates into ions, it causes freezing point depression. Hence Statement (II) is true.
Now examine Statement (I)

Statement (I): NaCl is added to the ice at $0^\circ\text{C}$ , present in the ice cream box to prevent the melting of ice cream.

When NaCl is added to ice, the freezing point of water decreases below $0^\circ\text{C}$ . As a result, the ice-salt mixture can attain a temperature lower than $0^\circ\text{C}$ .

This colder mixture absorbs heat from the surroundings and helps keep the ice cream mixture colder, thereby preventing the ice cream from melting (and in practice helping it freeze/stay solid).

Therefore Statement (I) is also true.
Evaluate options
- A: Both false → incorrect
- B: I true, II false → incorrect
- C: Both true → correct
- D: I false, II true → incorrect
Final conclusion

Both statements are true.

Hence the correct option is: $\boxed{\text{C}}$