Surface Chemistry Test

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Surface Chemistry Test - 57

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Weekly Quiz Competition

Question 1
1 / -0

The fresh precipitate can be transformed in colloidal solution by:

A
peptization

B
coagulation

C
diffusion

D
none of these

Solution

The dispersion of a freshly precipitated material into colloidal solution by the action of an electrolyte in solution is termed peptization. The electrolyte used is called a peptizing agent. For Example, sols obtained by peptization are: Freshly prepared ferric hydroxide on treatment with a small amount of ferric chloride solution at once forms a dark reddish brown solution. Ferric chloride acts as a peptizing agent.
Question 2
1 / -0

Cotrell precipitator works on the principle of:

A
distribution law

B
addition of electrolyte

C
neutralisation of charge on colloids

D
Le Chatelier's principle

Solution

Smoke coming out of the chimney in industrial area is a nuisance and health hazard. It is a colloidal particles which are charged particles and thus they are removed from fuel gases by electrical precipitation (Cottrell Precipitator) which involves neutralisation of charged colloidal particles present in the smoke.
Question 3
1 / -0

Activated charcoal is prepared by:

A
Adding $$Ba_3(PO_4)_2$$ to charcoal

B
Treatment with cone. $$HNO_3 $$

C
Heating charcoal with steam to make it more porous

D
Adding silica to charcoal

Solution

Activated charcoal is prepared by heating charcoal with steam to make it more porous.

Question 4

1 / -0

Match the Column-I with Column-II. Choose the correct' one from the alternatives (a), (b) , (c) and (d).

Column - I	Column-II
P. Wilkinson catalyst	I. trans -$$IrCl(CO)(PPh_3)_2$$
Q. Speier catalyst	II. Hydrosilylation
R. Water gas shift catalyst	III. $$RhCl (PPh_3)_3$$
S. Zeolite ZSM-5 catalyst	IV. Synthetic gasoline
	V. Hydroformylation
	VI. Zinc-copper oxide

(a) P- III (b) P- I (c) P- IV (d) P- III

(a) Q- II (b) Q- V (c) Q- II (d) Q- IV

(a) R- VII (b) R- III (c) R- VI (d) R- IV

(a) S- IV (b) S- IV (c) S- IV (d) S- II

Solution

(a) P- III (b) P- I (c) P- IV (d) P- III

Wilkinson catalyst is $$RhCl(PPh_3)_3$$.Speier catalyst is trans-$$UrCl(CO)(PPh_3)_2$$

Water gas shift catalyst is synthetic gasoline.

Zeolite ZSM-5 catalyst is $$RhCl(PPh_3)_3$$

Question 5
1 / -0

Which of the following represents physical adsorption ?

A

B

C

D

Solution

Physical adsorption decrease with increase in temparature.
So option A indicates the same
Hence option A is correct.
Question 6
1 / -0

Which of the following is an example of absorption?

A
Oxygen on metal surface

B
Hydrogen on finely divided nickel

C
Water on calcium chloride

D
Water on silica gel

Solution
Question 7
1 / -0

In which one of the following properties, physisorption and chemisorption resemble each other?

A
Force of attraction

B
Enthalpy of adsorption

C
Temperature effect

D
Effect of surface area

E
Number of adsorption layers

Solution

Physical and chemical adsorption resemble only in effect of surface area, as
(a) Force of attraction is more in case of chemical adsorption.
(b) Enthalpy of adsorption is more negative for chemical adsorption.
(c) Chemical adsorption depends on activation energy. Thus, it initially increases then decreases for increase in temperature. While physical adsorption only decreases with the increase in temperature.
(e) Physical adsorption is multilayered while chemical adsorption is single layer adsorption.
Question 8
1 / -0

Which is correct about physical adsorption?

A
High temperature and high pressure favour adsorption

B
High temperature and low pressure favour adsorption

C
Low temperature and high pressure favour adsorption

D
Low temperature and low pressure favour adsorption

E
Temperature and pressure have no effect on adsorption

Solution

Adsorption being an exothermic process, is favoured by low temperature (according to Le-Chatelier's principle).
Moreover, high pressure also favours adsorption, because during adsorption, volume of gases decreases along with liberation of heat.
Question 9
1 / -0

Choose the wrong statement from the following.

A
$$Ti{ O }_{ 2 }$$ is used in the pigment industry

B
$$Mn{ O }_{ 2 }$$ is used in dry battery cells

C
$${ V }_{ 2 }{ O }_{ 5 }$$ catalyses the oxidation of $$S{ O }_{ 2 }$$ in the manufacture of sulphuric acid

D
Ziegler-Natta catalyst is used in the manufacture of high density polyethylene

E
The 'silver' UK coins are made of $${ Ag }/{ Ni }$$ alloy

Solution

In the U.K., silver-coloured coins minted between 1947 and 2012 were made from $$\text{copper-nickel}$$. The nickel coin comprises 25 per cent nickel and 75 per cent copper and weighs five grams, according to the U.S. Mint.

Hence, option $$\text{E}$$ is a wrong statement.
Question 10
1 / -0

Which of the following curves represents the chemical adsorption?

A

B

C

D

Solution

solution:
$$log \dfrac{x}{m} = log k + 1 /n log p$$
$$\dfrac{x}{m}= k.p^1/ n $$(n > 1)
at low temp x/ m is small and as temperature is increased the molecules of the absorbate gain energy and become equal to activation energy so that proper bonds are formed with adsorbent molecules.
further increase in temperature will increase the energy of molecules which have already been adsorbed this would increase the rate of desorption and, therefore, decrease the extent of adsorption.
hence the correct opt: C