AP EAMCET · Chemistry · Solutions

At $T (K) xg$ of a non-volatile solid (molar mass $78 g {mol}^{- 1}$ ) when added to $0.5 kg$ water, lowered its freezing point by $1.0 ° C$ . What is $x$ (in $g$ ) ( $K_{f}$ of water at $T (K) = 1.86 {KKgmol}^{- 1}$ )

A $10.48$
B $20.96$
C $41.92$
D $5.24$

Verified Solution

Answer & Solution

Correct Answer

(B) $20.96$

Step-by-step Solution

Detailed explanation

Depression in freezing point is a colligative property.Hence, it depends on the number of solute particles. ΔTf=Kf×m m=Molality ΔTf=Freezing point of solvent-Freezing point of solution ΔTf=1.0∘C…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

Match the following.

List - $I$ Reaction		List - $II$ Catalyst
$(A)$	$N_{2} (g) + 3 H_{2} (g) ⟶ 2 {NH}_{3} (g)$	$(I)$	$Ni$
$(B)$	$2 H_{2} (g) + O_{2} (g) ⟶ 2 H_{2} O (l)$	$(II)$	$Pt$
$(C)$	$CO (g) + 3 H_{2} (g) ⟶ {CH}_{4} (g) + H_{2} O (g)$	$(III)$	$ZnO - {Cr}_{2} O_{3}$
$(D)$	$CO (g) + 2 H_{2} (g) ⟶ {CH}_{3} OH (g)$	$(IV)$	$Fe$

The correct answer is:

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At TKxg of a non-volatile solid (molar mass 78 g mol-1 ) when added to 0.5 kg water, lowered its freezing point by 1.0°C. What is x (in g) (Kf of water at T(K)=1.86 KKgmol-1)

Step-by-step Solution

At $T (K) xg$ of a non-volatile solid (molar mass $78 g {mol}^{- 1}$ ) when added to $0.5 kg$ water, lowered its freezing point by $1.0 ° C$ . What is $x$ (in $g$ ) ( $K_{f}$ of water at $T (K) = 1.86 {KKgmol}^{- 1}$ )