CBSE
Multiple Choice QuestionsThe freezing point of a solution containing 0.2 g of acetic acid in 20.0 g benzene is lowered by 0.45°C. The degree of association of acetic acid in benzene is (Assume acetic acid dimerises in benzene and Kf for benzene = 5.12K kg mol-1) Mobserved of acetic acid = 113.78
94.5%
54.9%
78.2%
100%
Which salt is insoluble in water ?
NH4Cl
KCl
Na2SO4
NaCl
Two elements A and B form compounds of formula AB2 and AB4. When dissolved in 20.0 g of benzene 1.0 g of AB2 lowers freezing point by 2.3°C whereas 1.0 g of AB4 lowers freezing point by 1.3°C. The Kf for benzene is 5.1. The atomic masses of A and B are
25, 42
42, 25
52, 48
48, 52
Assertion : Acetone and aniline shows negative deviations.
Reason : H-bonding between acetone and aniline is stronger than that between acetoneacetone and aniline-aniline.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false
If both assertion and reason are false.
60 g of urea is dissolved in 1100 g solution. To keep Tf/Kf as 1 mol kg-1 water separated in the form of ice is :
40 g
60 g
100 g
200 g
Vapour density of PCl5 (g) dissociating into PCl3 (g) and Cl2 (g) is 100. Hence, van't Hoff factor for the case :
PCl5 (g) PCl3 (g) + Cl2 (g) is :
1.85
3.70
1.085
1.0425
Which of the following can be measured by the Ostwald-Walker dynamic method ?
Relative lowering of vapour pressure
Lowering of vapour pressure
Vapour pressure of the solvent
All of the above
Assertion : A solution of sucrose in water is dextrorotatory. But on hydrolysis in the presence of a little hydrochloric acid, it becomes laevorotatory.
Reason : Sucrose on hydrolysis gives unequal amounts of glucose and fructose. As a result of this, change in sign ofrotation is observed.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
What happens when chloroform is left open in air in the presence of sunlight?
Explosion takes place
Phosgene, a poisonous gas is formed.
Polymerisation takes place.
No reaction takes place.
Osmosis involved in :
excretion of urine
interchange of nutrients and waste products betweeen tissue cells and their surroundings
in both cases
None of the above
