Evaluate the following statements for their correctness.
A. The elevation in boiling point temperature of water will be same for 0.1 M NaCl and 0.1 M urea.
B. Azeotropic mixtures boil without change in their composition.
C. Osmosis always takes place from hypertonic to hypotonic solution.
D. The density of 32 % H₂ SO₄ solution having molarity 4.09 M is approximately 1.26 g mL⁻¹
E. A negatively charged sol is obtained when KI solution is added to silver nitrate solution.
Choose the correct answer from the options given below :

Solution

Chemistry ma’am · 3 steps

Test each statement on its own; the classic traps are the van 't Hoff factor and the order of mixing.

1. Colligative effect. Δ T_b = i K_b m depends on the number of solute particles. NaCl splits into two ions (i = 2), while urea stays as one molecule (i = 1).
2. Density check. For a solution that is w% by mass, molarity = (10 × d × w)/M with d in g mL⁻¹. Rearranging gives d = (4.09 × 98)/(10 × 32) = 1.25 g mL⁻¹, which agrees with the stated value of about 1.26.

   Statement	Verdict	Reason
   A	False	NaCl gives twice as many particles, so its elevation is about double that of urea.
   B	True	The vapour of an azeotrope has the same composition as the liquid, so the composition does not change as it boils.
   C	False	Solvent moves from the hypotonic (dilute) side to the hypertonic (concentrated) side.
   D	True	d ≈ 1.25 g mL⁻¹, matching the stated value.
   E	False	AgNO₃ is in excess, so AgI adsorbs Ag⁺ and the sol is positive.

3. So. Only B and D are correct, which is option (c).

The idea to keep. In a sol, the ion that is in excess decides the charge. The flask you add to holds the excess. For colligative properties, always multiply by i before comparing.

Answer from the NTA final answer key. Solution by PrepWiser.