Surface Chemistry Test

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Surface Chemistry Test - 19

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Weekly Quiz Competition

Question 1
1 / -0

Soaking of water by a sponge is an example of :

A
simple adsorption

B
physical adsorption

C
chemisorption

D
absorption

Solution

Soaking of water by a sponge is an example of physical adsorption.

Water molecules are held to the surface of the sponge by weak van der Waals forces.

Hence, the correct option is B.
Question 2
1 / -0

A freshly formed precipitate of $$SnO_2$$ is peptized by a small amount of NaOH. These colloidal particles may be represented as :

A
$$[SnO_2]SnO_3^{2-}; 2Na^{\oplus}$$

B
$$[SnO_2]Sn^{4+}; O^{2-}$$

C
$$[SnO_2]Na^{\oplus}; OH^{\ominus}$$

D
$$[SnO_2]Sn^{4+}; OH^{\oplus}$$

Solution

A freshly formed precipitate of $$SnO_2$$ is peptized by a small amount of NaOH. These colloidal particles may be represented as :

$$[SnO_2]SnO_3^{2-}; 2Na^{\oplus}$$

$$SnO_2$$ adsorbes negatively charged $$SnO_3^{2-}$$ ions and is surrounded by $$Na^+$$ ions which maintains electrical neutrality.

Hence,option A is correct.
Question 3
1 / -0

In adsorption, the substance which accumulates on the surface of the other substance is termed as:

A
adsorbate

B
adsorbent

C
accumulator

D
none

Solution

In adsorption, the substance which accumulates on the surface of the other substance (adsorbent) is termed as adsorbate.
For example, anhydrous calcium chloride (adsorbent) adsorbs water (adsorbate).
Question 4
1 / -0

TEL, tetraethyl lead, acts as an anti-knocking agent. It acts as:

A
negative catalyst

B
catalyst

C
electophile

D
nucleophile

Solution

TEL act as a negative catalyst. It is an anti-knocking substance is added to petrol to decrease the ignition of petrol vapours.
Question 5
1 / -0

A catalyst promoter ___________ the efficiency of a catalyst while a poison ________ the efficiency of the catalyst.

A
decreases, increases

B
decreases, decreases

C
increases, increases

D
increases, decreases

Solution

A catalyst promoter increases the efficiency of a catalyst while a poison decreases the efficiency of the catalyst.

Substances which themselves are not catalysts but when mixed in small quantities with the catalysts increase their efficiency are called as promoters or activators. For example, in the Haber process for the synthesis of ammonia, traces of molybdenum increase the activity of finely divided iron which acts as a catalyst.

Substances that destroy the activity of the catalyst by their presence are known as catalytic poisons. For example, the platinum catalyst used in the oxidation of hydrogen is poisoned by $$CO$$.
Question 6
1 / -0

Intermediate compound formation theory explains:

A
homogeneous catalysis

B
heterogeneous catalysis

C
both of the above

D
none of the above
Question 7
1 / -0

Gelatin has the minimum protective powers.

A
True

B
False

C
Ambiguous

D
Data insufficient

Solution

As we know, smaller the gold number, higher the protective power of a colloid. Gold numbers of some protective colloids are given below :

Protective Colloid Gold Number
Haemoglobin 0.03 to 0.07
Starch 15 to 25
Gum Arabic 15 to 25
Gelatin 0.005 to 0.1

Therefore, gelatin has maximum protective powers.

Hence, option B is correct.
Question 8
1 / -0

Physical adsorption is appreciable at ............. temperature.

A
low

B
high

C
very high

D
moderate

Solution

Physical adsorption is appreciable at low temperature.
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 9
1 / -0

Adsorption is a process in which a substance accumulates on the ............. of the other substance.

A
surface

B
core

C
membrane

D
plasma

Solution

Adsorption is a process in which a substance accumulates on the surface of the other substance. It occurs when a gas or liquid solute accumulates on the surface of a solid or a liquid (adsorbent) forming a molecular or atomic film (the adsorbate). It is different from absorption in which a substance diffuses into a liquid or solid to form a solution. Thus adsorption is surface phenomenon whereas absorption is bulk property.
Question 10
1 / -0

Finely powered or colloidal catalyst particles having small surface area are rich in free valencies.
State whether the statement is True or False

A
The statement is True

B
The statement is False

C
Neither

D
Finely powered or colloidal catalyst particles having large surface area are rich in free valencies.

Solution

Finely powered or colloidal catalyst particles having small surface area cannot be rich in free valencies. When the catalyst is finely powdered the surface area of the particle is small but total surface area is very large.

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Surface Chemistry Test - 19

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Surface Chemistry Test - 19

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Question 1

simple adsorption

physical adsorption

chemisorption

absorption

Solution

Question 2

$$[SnO_2]SnO_3^{2-}; 2Na^{\oplus}$$

$$[SnO_2]Sn^{4+}; O^{2-}$$

$$[SnO_2]Na^{\oplus}; OH^{\ominus}$$

$$[SnO_2]Sn^{4+}; OH^{\oplus}$$

Solution

Question 3

adsorbate

adsorbent

accumulator

none

Solution

Question 4

negative catalyst

catalyst

electophile

nucleophile

Solution

Question 5

decreases, increases

decreases, decreases

increases, increases

increases, decreases

Solution

Question 6

homogeneous catalysis

heterogeneous catalysis

both of the above

none of the above

Question 7

True

False

Ambiguous

Data insufficient

Solution

Question 8

low

high

very high

moderate

Solution

Question 9

surface

core

membrane

plasma

Solution

Question 10

The statement is True

The statement is False

Neither

Finely powered or colloidal catalyst particles having large surface area are rich in free valencies.

Solution

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