Surface Chemistry Test

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Surface Chemistry Test - 50

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Weekly Quiz Competition

Question 1
1 / -0

Which one of the following characteristics is not correct for physical adsorption

A
Adsorption on solids is reversible

B
Adsorption increases with increase in temperature

C
Adsorption is spontaneous

D
Both enthalpy and entropy of adsorption are negative

Solution

Physical adsorption increases with decrease in temperature as easily liquifiable gases can adsorb more.
So option B is false statement.
Hence option B is correct
Question 2
1 / -0

Colloidal solutions of gold prepared by different methods have different colours owing to

A
The difference in the size of the colloidal particles

B
The fact that gold exhibhits a variable valency of +1 and +3

C
Different concentrations of gold

D
Presence of different types of forign particles depending upon the method of preperation of the colloid

Solution

The Gold colloidal solution prepared from different methods have different colors due to the different size of colloidal gold particles in the different solutions.
Question 3
1 / -0

$$ Fe(OH)_{3} $$ when treated with $$ Fe(OH)_{3} $$ solution a reddish-brown solution is formed. The process involved is

A
Dispersion

B
Exchange of solvent

C
Peptization

D
None of these

Solution

This process is known as peptization
Question 4
1 / -0

Physical adsorption is essentially quite appreciable

A
At room temperature

B
At higher temperature

C
At lower temperature

D
None of these

Solution

In physical adsorption, equilibrium is established between the adsorbate and the fluid phase. In solid or gas systems, at not too high pressures, the extent of physical adsorption increases with increase in gas pressure and usually decreases with increasing temperature. Since physical adsorption is an exothermic process, the rate of physical adsorption is inversely proportional to temperature.
Question 5
1 / -0

Adsorption is phenomenon in which a substance

A
Goes into the body of the other substance

B
Remains close the other substance

C
Accumulates on the surface of the other substance

D
None of these

Solution

Adsorption is the phenomenon in which a substance accumulates on the surface of the other substance.
Question 6
1 / -0

Which are not purely surface phenomena?

A
Adsorption , surface tension

B
Surface tension , viscosity

C
Adsorption , viscosity

D
Absorption , viscosity
Solution
- Adsorption - It is the phenomenon of accumulation of large number of molecular species at the surface of liquid or solid phase in comparison to the bulk. The process of adsorptionarises due to presence of unbalanced or residual forces at the surface of liquid or solid phase.
Surface tension- The cohesive forces between liquid molecules are responsible for the phenomenon known as surface tension. This forms a surface "film" which makes it more difficult to move an object through the surface than to move it when it is completely submersed.
Viscosity- Viscosity is a measure of a fluid's resistance to flow. It is a bulk property of the fluid and by extension of this, it is not only a surface property.
Absorption - Absorption is assimilation of the molecular system throughout the bulk of the solid or liquid medium. Thus, it is a bulk phenomenon.
Hence, option D is correct.
Question 7
1 / -0

Which of the following metal sols cannot be prepared by Bredig's arc method?

A
Copper

B
Potassium

C
Gold

D
Platinum
Question 8
1 / -0

For a given reaction, energy of activation for forward reaction $$(E_{af})$$ is $$80kJ.mol^{-1}.$$ $$\Delta H = -40kJ.mol^{-1}$$ for the reaction. A catalyst lowers $$E_{af}$$ to $$20 kJ.mol^{-1}.$$ The ratio of energy of activation for reverse reaction before and after addition of catalyst is :

A
1.0

B
0.5

C
1.2

D
2.0

Solution

$$\Delta$$ H = E$$_{f}$$ E$$_{b}$$ -40 = 80 - E$$_{b}$$ E$$_{b}$$ = 120 kJ/mole,
catalyst lower the E$$_{f}$$ To 20 kJ/ mole for forward Rxn then E$$_{f}$$' = 20 kJ/mol
we know catalyst decreases the Activation energy equal amount
in both direction
E$$_{b}'= (120 60)$$ $$= 60 kJ/mol$$
$$\frac{E_{b}}{E'_{b}}=\frac{120}{60}$$=2.0
Question 9
1 / -0

Which is wrong about a positive catalyst?

A
It lowers the energy of activation of forward reaction

B
It lowers the threshold energy level

C
It lowers the energy of activation of backward reaction

D
It makes the reaction more exothermic or endothermic

Solution

Catalyst cannot make the reaction more exothermic or endothermic.

$$\Delta H = E_{a(f)} - E_{a(b)}$$ is fixed for a reaction since catalyst change the activation by equal magnitude in both forward and backward reaction.
Question 10
1 / -0

Identify an emulsion from among the following.

A
Ruby

B
Sponge

C
Milk

D
Jellies

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Re-Attempt Weekly Quiz Competition

Surface Chemistry Test - 50

Result

Surface Chemistry Test - 50

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Rank

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SHARING IS CARING

Question 1

Adsorption on solids is reversible

Adsorption increases with increase in temperature

Adsorption is spontaneous

Both enthalpy and entropy of adsorption are negative

Solution

Question 2

The difference in the size of the colloidal particles

The fact that gold exhibhits a variable valency of +1 and +3

Different concentrations of gold

Presence of different types of forign particles depending upon the method of preperation of the colloid

Solution

Question 3

Dispersion

Exchange of solvent

Peptization

None of these

Solution

Question 4

At room temperature

At higher temperature

At lower temperature

None of these

Solution

Question 5

Goes into the body of the other substance

Remains close the other substance

Accumulates on the surface of the other substance

None of these

Solution

Question 6

Adsorption , surface tension

Surface tension , viscosity

Adsorption , viscosity

Absorption , viscosity

Solution

Question 7

Copper

Potassium

Gold

Platinum

Question 8

1.0

0.5

1.2

2.0

Solution

Question 9

It lowers the energy of activation of forward reaction

It lowers the threshold energy level

It lowers the energy of activation of backward reaction

It makes the reaction more exothermic or endothermic

Solution

Question 10

Ruby

Sponge

Milk

Jellies

User

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My Perfomance

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