Camphor is often used in molecular mass determination because

it is readily available
it has a very high cryoscopic constant
it is volatile
it is solvent for organic substances

Solution

Solvent having high cryoscopic constant (camphor)can be used in determination of molecular masses of organic compounds like naphthalene, anthraceneetc.,by cryoscopic method.

Which of the following colligative property can provide molar mass of proteins(or polymers or colloids) with greatest precision ?

Osmotic pressure
Elevation of boiling point
Depression of freezing point
Relative lowering of vapour pressure

Solution

Molecular masses of polymers are best determined by osmotic pressure method. Firstly because other colligative properties give so low values that they cannot be measured accurately and secondly, osmotic pressure measurements can be made at room temperature and do not require heating which may change the nature of the polymer.

Which of the following 0.10 m aqueous solutions will have the lowest freezing point ?

Al₂(SO₄)₃
C₆H₁₂O₆
KCl
C₁₂H₂₂O₁₁

Solution

Which one of the following salts will have the same value of van’t Hoff factor (i) as that of K₄[Fe(CN)₆].

Al₂(SO₄)₃
NaCl
Al(NO₃)₃
Na₂SO₄.

Solution

At 25°C, the highest osmotic pressure is exhibited by 0.1 M solution of

CaCl₂
KCl
glucose
urea

Solution

Concentration of particles in CaCl₂ solution will be maximum as i= 3 for CaCl₂ and i= 2 for KCl. Glucose and Urea do not dissociate into ions, as they are non electrolytes.

When 800 gm of a 40% solution by weight was cooled, 100 gm of solute precipitated. The percentage composition of remaining solution is

31.43%
5.56%
6.78%
6.96%

Solution

If 0.1 M solution of glucose and 0.1 M solution of urea are placed on two sides of the semipermeable membrane to equal heights, then it will be correct to say that

there will be no net movement across the membrane
glucose will flow towards urea solution
urea will flow towards glucose solution
water will flow from urea solution to glucose

Solution

As both the solutions are isotonic hence there is no net movement of the solvent occurs through the semipermeable membrane between two solutions.

Which one of the following is a colligative property ?

Boiling point
Vapour pressure
Osmotic pressure
Freezing point

Solution

Osmotic pressure is a colligative property.

5 gm of CHCOOH₃ is dissolved in one litre of ethanol.Suppose there is no reaction between them. If the density of ethanol is 0.789 gm/ml then the molality of resulting solution is

0.0256
0.1056
0.1288
0.1476

Solution

On adding 0.750 gm of compound in 25 gm of solvent, the freezing point is depressed by 0.502°C. The molecular wt. of the substance is [The molecular depression constant =50.2°C per 100 gm of solvent]

Solution

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