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ISC Class 12 Chemistry Solved Question Paper 2004

Short Answer Type

31.

How will you convert the following (write the relevant equations) :
Glucose to osazone.

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32. Compare the components that constitute DNA and RNA.

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Long Answer Type

33. Define osmotic pressure. Arrange the following in increasing order of osmotic pressure and give reasons in support of your answer :

Osmotic Pressure. The pressure which is applied to the solution in order to prevent the passage of solvent into it through a semi-permeable membrane present between the two is termed as osmotic pressure.

We know that osmotic pressure is a colligative property and hence it depends on the number of solute particles.
$straight i right parenthesis space Mole space of space Sucrose space equals space fraction numerator 34.2 over denominator 342 end fraction space equals space 0.1 ii right parenthesis space Mole space of space Glucose space equals space 90 over 180 space equals space 0.5 iii right parenthesis space Mole space of space NaCl space equals space fraction numerator 5.85 over denominator 58.5 end fraction space equals space 0.1$

Since 1 mole = 6.023 x 10²³ particles

So Sucrose = 6.023 x 10²² particles

(As Sucrose and Glucose are undissociated)

Glucose = 30.115 x 10²² particles

NaCl = 12.046 x 10²² particles.

(NaCl dissociates to give two ions)

Hence, the increasing order of their osmotic pressure is, Sucrose < NaCl < Glucose.

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34.

A cell is constructed by dipping a zinc rod in 0.1 M zinc nitrate solution and a lead rod in 0.2 M lead nitrate solution. E°_pb²⁺/pb =-0.13 V and E°_{Zn²⁺/ Zn}=–0.76 V. [3]

(i) Write the spontaneous cell reaction.

(ii) Calculate standard emf and emf of the cell.

(b) Explain the purification of common salt by bubbling hydrogen chloride gas through its solution.

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