Question

Compare boiling point of given solutions:

(i) \( 10^{-4} \, \text{M NaCl} \)>(ii) \( 10^{-3} \, \text{M NaCl} \)>(iii) \( 10^{-2} \, \text{M NaCl} \)>(iv) \( 10^{-4} \, \text{M urea} \) 

(iii) \( 10^{-2} \, \text{M NaCl} \)>(ii) \( 10^{-3} \, \text{M NaCl} \)>(i) \( 10^{-4} \, \text{M NaCl} \)>(iv) \( 10^{-4} \, \text{M urea} \) 

(ii) \( 10^{-3} \, \text{M NaCl} \)>(i) \( 10^{-4} \, \text{M NaCl} \)>(iii) \( 10^{-2} \, \text{M NaCl} \)>(iv) \( 10^{-4} \, \text{M urea} \) 

(iii) \( 10^{-2} \, \text{M NaCl} \)>(ii) \( 10^{-3} \, \text{M NaCl} \)>(i) \( 10^{-4} \, \text{M NaCl} \)>(iv) \( 10^{-4} \, \text{M urea} \) 
 

• A. \( i>ii>iii>iv \)
• B. \( iii>ii>i>iv \)
• C. \( ii>i>iii>iv \)
• D. \( iii>ii>i>iv \)

Hint:

Boiling point elevation is directly related to the molality of the solution and the number of dissociated particles.

Answer 1

The Correct Option is B

Higher the elevation in boiling point, higher will be the boiling point

\( \Delta T_b \propto i \times m \)

For urea \( i = 1 \)

For NaCl \( i = 2 \)

Boiling point order: III>II>I>IV