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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