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Daily Practice Problems
Class 12 Chemistry
Solutions
daily practice problem

Question1.

Calculate (a) molarity (b) molality and (c) mole fraction of KI if the density of 17% (mass/mass) aqueous KI is 1.6gml-1.

Question2.

The freezing point order of a solution of glucose is –

(a) 1% > 3% > 10% > 2%

(b) 1% >  2% >  3% >10%

(c)  1% > 3% > 10% > 2%

(d) 10%> 3% > 2% > 1%  

Question3.

H2S, a toxic gas with rotten egg like smell, is used for qualitative analysis. If the solubility of H2S in water at STP is 0.19m, calculate Henry’s law constant.

Question4.

Give relation between molarity and mole fraction.

Question5.

Calculate the mass of Blue vitriol (CuSO4.2H2O) that should be dissolved to prepare 100ml of 0.75 M Aqueous solution. (MB = 159.6g).

Question6.

What concentration of nitrogen should be present in a glass of water at room temperature? Assume temeprature of 250C, a total pressure of 1 ATM and mole fraction of nitrogen in air of 0.78 [ KH For nitrogen = 8.42 x 10-7 M/mm Hg ]

Question7.

 1.2% solution of NaCl is isotonic with 7.2% solution of cane sugar. Calculate Van’t  Hoff factor of NaCl.

Question8.

Define the following terms:

(i) Ideal solutions

(ii) Azeotrope

(iii) Reverse osmosis

Question9.

The concentration of NO2 in M.P is 11 ppm by volume. Calculate the volume of NO2 per litre of the atmospheric air.

Question10.        

Addition of 1.3g of a solute B to 169 g of water raises its boiling point to 100.250C at 1 atm. Compute MB when Kb ( water) is 0.52 K kg mol-1.

Question11.

The osmotic pressure of solution containing 0.10 g of haemoglobin in 10 ml of solution is 2.67 torr at 274 K. Find the molar mass of haemoglobin.

Question12.

Match the following:

(a) Molal elevation constant (kb)                 -                JK-1Mol-1

(b) Roult’s law                                                 -                MolKg-1                       

(c) Van off factor                                              -                mmHg

(d) Gas constant                                                -                KKg-1Mol-1

(e) Molality                                                         -                Unit less

Question13.

What is van’t Hoff factor? How does it help in the determination of degree of association or dissociation of solute in a solution?

Question14.

What is positive deviation and negative deviation with graphical representation?

 

Question15.

Vapour pressure of water at room temperature is 23.8mm of hg. What will be the vapour pressure of aqueous solution of sucrose with mole fraction equal to 0.1?

Question16.

What happens when we placed blood in water (hypertonic solution)? Give reason.

Question17.

Which of the following statement is false?

(a) Two different solution of sucrose of same molality prepared in different solvent will have the same depression in freezing

(b) The osmotic pressure of a solution is given by the equation  𝛑 = CRT ( where C is the molarity of the solution)

(c) Decreasing order of osmotic pressure for 0.01M aqueous solution of barium chloride, potassium chloride, acetic acid and sucrose is,

BaCl2 > KCl > CH3COOH > Sucrose

(d) According to Raoult’s law, the vapour pressure exerted by a volatile component of a solution is directly proportional to its mole fraction in the solution.

uestion18.

For a solvent (A) Kf = 31.8 K Kg mol-1 and Kb 5.03 K Kg mol-1. When 3g of a non-volatile solute B is dissolved in 100g of A, the freezing Point is lowered by 3.8 K.

Compute:

(a0 Molar mass of solute (Mb)

(b)  Elevation of boling point (∆Tb)

(c) Relative lowering of vapour pressure 

(d) Osmotic pressure π at 300K

Take density of solvent 1.60 g cm-3 and its molar mass (Kb) = 0.154

Question19.

Why does the azeotropic mixture distil without any change in composition?

Question20.

Which of the following fluoride is used as rat poison?

(a) CaF2

(b) KF

(c) NaF

(d) MgF2

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