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The freezing point of a diluted milk sample is found to be -0.2^{0}C , while it should have been -0.5^{0}C for pure milk. How much water has been added  to pure milk  to make the diluted sample ?

  • Option 1)

    2 cups of water to 3 cups of pure milk.

  • Option 2)

    3 cups of water to 2 cups of pure milk.

  • Option 3)

    1 cup of water to 3 cups of pure milk.

  • Option 4)

    1 cup of water to 2 cups of pure milk.

Answers (1)

best_answer

 

Depression in freezing point -

-

 

 

 

Freezing -

 Freezing  occurs when liquid solvent is in equilibrium with solid solvent. As non volatile solute decreases, the vapour pressure freezing point decreases.

-As we knoew that

Freezing point of milk = -0.5^{0}C\because \Delta T_{f}= 0.5^{0}C

Freezing point of milk (diluted)=-0.2^{0}C \because \Delta T_{f}= 0.2^{0}C

\frac{\left ( \Delta T_{f} \right )i}{\left ( \Delta T_{f} \right )ii}= \frac{0.5}{0.2}= \frac{K_{f}m}{K_{f}m}= \frac{x\left ( mole \right )\times weight\left ( 2 \right )}{weight_{\left ( 1 \right )\times }x\left ( mole \right )}

W_{2}= \frac{5}{2}W_{1}

 

 

 


Option 1)

2 cups of water to 3 cups of pure milk.

Option 2)

3 cups of water to 2 cups of pure milk.

Option 3)

1 cup of water to 3 cups of pure milk.

Option 4)

1 cup of water to 2 cups of pure milk.

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