Saraswati Vidhya Mandir, Gandhinagar
Chapters : 1,2 Std 12 : Chemistry Date : 05/07/25
Total Marks : 39 Unit Test Time : 03 Hour
//X Section A
• Write the answer of the following questions. [Each carries 3 Marks] [3]
1. If depression in freezing point of a solution prepared by dissolving 1 gram benzoic acid to the 25
gram of benzene is 0.81 Kelvin then find out degree of association. Molal depression constant of
solvent is 4.9 Kelvin kilogram mole–1.
//X Section B
• Write the answer of the following questions. [Each carries 4 Marks] [36]
2. Write Raoult’s law for non-volatile solute and volatile solvent. Derive it and also write two limitations
of it.
3. Write about Raoult’s law for non-volatile solute and prove it. Write the formula to find out molecular
mass of solute according to above rule.
4. Write Van’t Hoff law of osmotic pressure and explain its mathematical formation and also derive the
formula to identify osmotic pressure.
5. Two elements A and B form compounds having formula AB2 and AB4. When dissolved in 20g of
benzene (C6H6), 1g of AB2 lowers the freezing point by 2.3 K whereas 1g of AB4 lowers it by 1.3 K.
The molal depression constant for benzene is 5.1 K kg mol–1. Calculate atomic masses of A and B.
6. Calculate the depression in the freezing point of water when 10 g of CH3CH2CHCl COOH is added
to 250 g of water. [Ka = 1.4 × 10–3, Kf = 1.86 K kg mol–1]
(Atomic mass : H = 1, C = 12, O = 16, Cl = 35.5)
7. (i) 18 g of glucose (C6H12O6) is dissolved in 1 kg of water in a saucepan. At what temperature will
the solution boil at 1.013 bar ? Kb for water is 0.52 K kg mol–1 [C = 12, H = 1, O = 16 g mol–1]
(ii) 200 cm3 of aqueous solution contains 1.26 g of the protein. The osmotic pressure of such a
solution at 300 K is found to be 2.57 ´ 10–3 bar. Calculate the molar mass of the proteins.
8. 0.6 mL of CH3COOH having density 1.06 g mL–1 is dissolved in 1 litre of water. The depression in
freezing point observed for this strength of acid was 0.0205 °C. Calculate the Van’t Hoff factor and the
dissociation constant of acid (Kf = 1.86 K kg mol–1 and molecular mass of CH3COOH = 60 g mol–1)
9. 2g of benzoic acid (C6H5COOH) dissolved in 25g of benzene shows depression in freezing point
equal to 1.62K molal depression constant for benzene is 4.9 K kg mol–1. What is the percentage
association of acid if forms dimer in solution ? (Molecular mass of benzoic acid is 122 g mol–1)
10. Vapour pressure of chloroform (CHCl3) and dichloromethane (CH2Cl2) at 298 K are 200 mm Hg and
415 mm Hg respectively.
(i) Calculate the vapour pressure of the solution prepare by mixing 50 g of CHCl3 and CH2Cl2 at
298 K.
(ii) Calculate mole fractions of each component in vapour phase. (Atomic mass : H = 1, C = 12, Cl
= 35.5)
Wish You - All The Best
Saraswati Vidhya Mandir, Gandhinagar
Chapters : 1,2 Std 12 : Chemistry Date : 05/07/25
Total Marks : 39 Unit Test Time : 03 Hour
Section [ A ] : 3 Marks Questions
No Ans Chap Sec Que Universal_QueId
1. -
Welcome To Future - Quantum Paper
Saraswati Vidhya Mandir, Gandhinagar
Chapters : 1,2 Std 12 : Chemistry Date : 05/07/25
Total Marks : 39 Unit Test Time : 03 Hour
//X Section A
• Write the answer of the following questions. [Each carries 3 Marks] [3]
1.
//X Section B
• Write the answer of the following questions. [Each carries 4 Marks] [36]
2.
3.
4.
5.
6.
7.
8.
9.
10.
Welcome To Future - Quantum Paper
Welcome To Future - Quantum Paper
