Question

Which of the following has highest freezing point?
(a)0.1 m urea
(b) 0.2 m sucrose
(c) 0.3 m fructose
(d) 0.5 m glucose​

Answer 1

Answer:

Molarity of solutions

To find

Solution having maximum boiling point

Concept

Boiling point of water is 100 °C. It increases due to the presence of solid solute like urea, glucose, sucrose etc. Elevation in boiling point is directly proportional to molality of the solution .This is because, elevation in boiling point has the formula

∆T = k_{b}m < /p > < p > < /p > < p > where \: k_{b} = molal \: elevation \: constant < /p > < p > < /p > < p > and , m \: = \: molalityk

b

m</p><p></p><p>wherek

b

=molalelevationconstant</p><p></p><p>and,m=molality

Solution

For dilution solution , molality is nearly equal to molarity. Hence, that solution will have highest elevation in boiling point which has higher molarity .

Hence, the answer is 0.4 M fructose

Explanation:

hope it helps you

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Answer 2

Correct answer is Option (b) 0.2 m sucrose

Explanation:

• Concentration of the solute as well the nature of the solute is directly proportional to the freezing point of a solution

         Formula Used: ΔTf=i (Kf. m)

        Where, ΔTf is the change in the freezing point,

        Kf is the cryogenic constant, i is the Van’t Hoff factor and

        m is the molality of the solution.

• Ionic solutions are present which involve the dissociation into ions.

• Each and every ion must be taken into consideration because they contributes to the variation of physical properties.

• To rectify  use a correction factor which is  known as the Van’t Hoff factor.

         Using the formula, we get:

         0.2 m sucrose

          Sucrose is a non – ionic compound, hence i = 1.

          ΔTf  = (1) (0.2 Kf ) = 0.1 Kf

        Option (b) 0.2 m sucrose

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