1
MCQ (Single Correct Answer)

NEET 2016 Phase 2

The coagulation values in millimoles per litre of the electrolytes used for the coagulation of As2S3 are given below :
I.  (NaCl) = 52,
II. (BaCl2) = 0.69,
III. (MgSO4) = 0.22
The correct order of their coagulating power is
A
I > II > III
B
II > I > III
C
III > II > I
D
III > I > II

Explanation

As,

Coagulating power $$\infty $$
1
Coagulation value


Lower the coagulation value, higher is the coagulating power so, the correct order is :

III > II > I
2
MCQ (Single Correct Answer)

NEET 2016 Phase 1

Which one of the following characteristics is associated with adsorption?
A
$$\Delta $$G and $$\Delta $$H are negative but $$\Delta $$S is positive.
B
$$\Delta $$G and $$\Delta $$S are negative but $$\Delta $$H is positive.
C
$$\Delta $$G is negative but $$\Delta $$H and $$\Delta $$S are positive.
D
$$\Delta $$G, $$\Delta $$H and $$\Delta $$S all are negative.

Explanation

Adsorption is spontaneous process, therefore change in the free energy ( $$\Delta $$G) for the process is negative.

As we know that

$$\Delta $$G = $$\Delta $$H – T$$\Delta $$S

S is negative because adhering of gas molecules to the surface lowers the randomness.

$$ \therefore $$ $$\Delta $$G can be –ve only when $$\Delta $$H is –ve.
3
MCQ (Single Correct Answer)

AIPMT 2015 Cancelled Paper

Which property of colloidal solution is independent of charge on the colloidal particles?
A
Electro-osmosis
B
Tyndall effect
C
Coagulation
D
Electrophoresis

Explanation

Tyndall effect is the scattering of light by sol particles which cannot be affected by charge on them.
4
MCQ (Single Correct Answer)

AIPMT 2014

Which property of colloids is not dependent on the charge on colloidal particles?
A
Coagulation
B
Electrophoresis
C
Electro-osmosis
D
Tyndall effect

Explanation

Tyndall effect is due to the scattering of light by colloidal particles and not due to the charge.

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