JEE Main201911 Jan 2019Morning ShiftChemistrySolutionsActual
The freezing point of a diluted milk sample is found to be -0.2^ C , while it should have been -0.5^ C for pure milk. How much water has been added to pure milk to make the diluted sample?
Options
- A1 cup of water to 2 cups of pure milk
- B3 cups of water to 2 cups of pure milk
- C1 cup of water to 3 cups of pure milk
- D2 cups of water to 3 cups of pure milk
Correct answer
B. 3 cups of water to 2 cups of pure milk
Step-by-step solution
Freezing point of diluted milk =-0.2^ C T _ f ^ * =0.2^ C Free ring point ol pure milk =-0.5^ C T _ f =0.5^ C T _ f T _ f ^ = K _ f m ~K _ f m^ ; m= mole of solute mass of solvent ( kg ) Moles of solute are same in both samples. 0.5 0.2 = W ^ n ~W W ^ W = 5 2 ; W ^ = 5 2 ~W 2 cups of pure milk is mixed with 3 cups of water to make 5 cups of diluted milk.