KCET2026ChemistrySolutions
Which of the following is CORRECT with respect to the property mentioned against it?
Options
- AOsmotic pressure at 298 K: 0.1 M NaCl solution <0.1 M Urea solution
- BConcentration of NaCl in the solution 2 ppm > 2 M
- CT_b : 0.02 M Urea solution > 0.02 M NaCl solution
- DVapour pressure at 298 K: Salt water < Pure water
Correct answer
D. Vapour pressure at 298 K: Salt water < Pure water
Step-by-step solution
Osmotic pressure is given by = iCRT . For NaCl, the van't Hoff factor i = 2 , and for urea, i = 1 . Thus, the osmotic pressure of 0.1 M NaCl is greater than that of 0.1 M urea. Concentration of 2 ppm means 2 mg of solute per liter of solution, which is much less than 2 M NaCl ( 117 g per liter). Elevation in boiling point is given by T_b = iK_bm . Since i = 2 for NaCl and i = 1 for urea, T_b for 0.02 M NaCl is greater than that for 0.02 M urea. Addition of a non-volatile solute (salt) to a volatile solvent (water)