Q.54. Which of the following are not correct?
A. For water, magnitude of is more than the magnitude

Q: What is the correct answer for JEE Main Chemistry Q54?

The correct answer is A,B,D. Sol. (A) $K_f$ for water = $1.86 \mathrm{°C\cdot kg/mol}$. $K_b$ for water = $0.512 \mathrm{°C\cdot kg/mol}$. So, $K_f > K_b$. Statement A is incorrect. (B) For the same molality, $\Delta T_f = K_f m$ and $\Delta T_b = K_b m$. Since $K_f > K_b$, $\Delta T_f > \Delta T_b$. Therefore, the depression in freezing point is larger than the elevation in boiling point. Statement B is incorrect. (C) Osmoti

Q: Q.54. Which of the following are not correct? A. For water, magnitude of is more than the magnitude of . B. The elevation in boiling point of water when a non-volatile solute is added to it is…

The correct answer is A,B,D. Sol. (A) $K_f$ for water = $1.86 \mathrm{°C\cdot kg/mol}$. $K_b$ for water = $0.512 \mathrm{°C\cdot kg/mol}$. So, $K_f > K_b$. Statement A is incorrect. (B) For the same molality, $\Delta T_f = K_f m$ and $\Delta T_b = K_b m$. Since $K_f > K_b$, $\Delta T_f > \Delta T_b$. Therefore, the depression in freezing point is larger than the elevation in boiling point. Statement B is incorrect. (C) Osmoti

Q: What are the options for this JEE Main Chemistry question?

A. A and B only · B. A and D only · C. A, B and D only · D. A, C and D only

Question

Q.54. Which of the following are not correct?
A. For water, magnitude of  is more than the magnitude of .
B. The elevation in boiling point of water when a non-volatile solute is added to it is larger in magnitude than its depression in freezing point.
C. Osmotic pressure measurement is preferred over any other colligative property to determine molar mass of proteins and polymers.
D. The dimerised form of benzoic acid in benzene is CH-C(=O)-OH .... O=C-CH.
Choose the correct answer from the options given below:

FirstInTest · Accepted Answer

Sol. (A) $K_f$ for water = $1.86 \mathrm{°C\cdot kg/mol}$. $K_b$ for water = $0.512 \mathrm{°C\cdot kg/mol}$.
So, $K_f > K_b$. Statement A is incorrect.
(B) For the same molality, $\Delta T_f = K_f m$ and $\Delta T_b = K_b m$. Since $K_f > K_b$, $\Delta T_f > \Delta T_b$. Therefore, the depression in freezing point is larger than the elevation in boiling point. Statement B is incorrect.
(C) Osmotic pressure is preferred for determining molar masses of macromolecules like proteins and polymers because it is measured at room temperature, and the magnitude of osmotic pressure is significant even for dilute solutions, allowing for accurate measurements. Statement C is correct.
(D) The dimerised form of benzoic acid in benzene involves hydrogen bonding between two benzoic acid molecules, forming a cyclic dimer. The structure is C$_6$H$_5$-C(=O)-OH .... O=C-C$_6$H$_5$ (where the hydrogen of one -OH bonds to the oxygen of the other C=O, and vice versa). The structure shown in the question, C$_6$H$_5$-C-OH .... O=C-C$_6$H$_5$ with O-H----O and C=O----H-O, is incorrect. It should be C$_6$H$_5$-C(=O)-OH .... O=C(OH)-C$_6$H$_5$ or similar. The given structure is C$_6$H$_5$-C(O-H----O=C)-C$_6$H$_5$ which is not the standard dimer. Statement D is incorrect.
Therefore, options A, B, and D are incorrect.

Answer

A and B only

Answer

A and D only

Answer

A, B and D only

Answer

A, C and D only

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