Which of the following will show Tyndall effect?

At high concentration, soap solution behaves as associated colloid and form micelles. But micelles formation occurs only above Kraft temperature(T_K) and above critical micelle concentration(CMC). Colloidal particles can only show Tyndall effect. So (ii) is correct.

Option (i) is wrong because below critical micelle concentration soap solution cannot form micelle and thus can’t behave as colloids.so they don’t show Tyndall effect.

Aqueous solution of sodium chloride behaves as strong electrolyte and is dissociated into Na⁺ and Cl^- ions which don’t have colloidal particle size. So (iii) is not correct.

Aqueous solution of sugar is a non-electrolyte. Sugar molecules cannot aggregate to form colloidal sized particle. Therefore, option (iv) is also wrong.