Surface Chemistry Test

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Surface Chemistry Test - 70

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Weekly Quiz Competition

Question 1
1 / -0

Which one of the following changes when catalyst is used in a reaction?

A
Heat of reaction

B
Product of reaction

C
Equilibrium constant

D
Activation energy

Solution

Activation energy changes when catalyst is used in a reaction. Catalyst lowers the activation energy.
Question 2
1 / -0

A catalyst

A
Increases the free energy change in the reaction

B
Decreases the free energy change in the reaction

C
Does not increase or decrease the free energy change in the reaction

D
Can either increase or decrease the free energy change depending on what catalyst we use

Solution

Catalyst does not depend on the free energy change in the reaction nor it changes the free energy. It only enhances the rate of the reaction by lowering the activation.
Question 3
1 / -0

Hydrolysis ethyl acetate is catalysed by aqueous

A
$$Na_{2}SO_{4}$$

B
$$K_{2}SO_{4}$$

C
$$H_{2}SO_{4}$$

D
$$BaSO_{4}$$

Solution

$$ CH_{3}CHOOC_{2}H_{5}+HOH\xrightarrow[catalyst]{conc.\ H_{2}SO_{4}}CH_{3}COOH+C_{2}H_{5}OH $$

$$H_{2}SO_{4}$$ is used as a catalyst in hydrolysis ethyl acetate.
Question 4
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In the reversible reaction a catalyst is the substance which

A
Increases the rate of the forward reaction

B
Deceases the value of enthalpy change in the reaction

C
Reduces the time required for reaching the equilibrium state in the reaction

D
Decreases the rate of the reverse reaction

Solution

In the reversible reaction, a catalyst is a substance that reduces the time required for reaching the equilibrium state in the reaction. It enhances the rate of reaction by lowering the activation energy.
Question 5
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The emulsifying agent in milk is

A
Lactic acid

B
Casein

C
Lactose

D
Fat

Solution

Casein is the emulsifying agent in milk which keeps two immiscible layers of fat and water together.
Question 6
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Which is not a characteristic of a catalyst

A
It changes the equilibrium constant

B
It alters the reaction path

C
It increases the rate of reaction

D
It increases the average K.E. of the molecules

Solution

Equilibrium constant cannot be changed upon addition of catalyst as catalyst affects both forward and backward reactions to the same extent and hence don't alter the equilibrium constant. Rather it provides an alternative path wth lower activation energy to fasten the reaction.
Question 7
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The colloidal solution of mercury in water can be easily obtained by

A
Mechanical precipitation

B
Bredig's arc method

C
Repeated washing

D
Ultrasonic dispersion

Solution

A colloidal solution of certain elements such as mercury and sulphur is obtained by passing their vapors through cold water containing a stabilizer ( an ammonium salt or citrate).
Question 8
1 / -0

An emulsion is a colloidal dispersion of

A
A liquid in a gas

B
A liquid in a liquid

C
A solid in a liquid

D
A gas in a solid

Solution

An emulsion is a colloidal dispersion of a liquid in either a liquid or a solid. A stable emulsion requires an emulsifying agent to be present.
Question 9
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Which one of the following statements is correct in a reversible reaction?
A catalyst-

A
increases the rate of forward reaction

B
decreases the rate of forward reaction

C
increases the rate of backward and forward reactions

D
alters the equilibrium constant of the reaction

Solution

In a reversible reaction, the catalyst decreases the activation energy of both, forward and backward reactions.

Catalyst provides an alternate pathway of lower activation energy for the reaction.

Hence the correct option is C.
Question 10
1 / -0

Which of the following statements is true for a catalyst?

A
It increases the energy of the reactants

B
It decreases the energy of the products

C
It decreases the energy of the reactants

D
It does not change the enthalpy of the reactants

Solution

Catalyst does not change on the enthalpy of the reactants. It enhances the rate of the reaction by lowering the activation.

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Surface Chemistry Test - 70

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Surface Chemistry Test - 70

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Question 1

Heat of reaction

Product of reaction

Equilibrium constant

Activation energy

Solution

Question 2

Increases the free energy change in the reaction

Decreases the free energy change in the reaction

Does not increase or decrease the free energy change in the reaction

Can either increase or decrease the free energy change depending on what catalyst we use

Solution

Question 3

$$Na_{2}SO_{4}$$

$$K_{2}SO_{4}$$

$$H_{2}SO_{4}$$

$$BaSO_{4}$$

Solution

Question 4

Increases the rate of the forward reaction

Deceases the value of enthalpy change in the reaction

Reduces the time required for reaching the equilibrium state in the reaction

Decreases the rate of the reverse reaction

Solution

Question 5

Lactic acid

Casein

Lactose

Fat

Solution

Question 6

It changes the equilibrium constant

It alters the reaction path

It increases the rate of reaction

It increases the average K.E. of the molecules

Solution

Question 7

Mechanical precipitation

Bredig's arc method

Repeated washing

Ultrasonic dispersion

Solution

Question 8

A liquid in a gas

A liquid in a liquid

A solid in a liquid

A gas in a solid

Solution

Question 9

increases the rate of forward reaction

decreases the rate of forward reaction

increases the rate of backward and forward reactions

alters the equilibrium constant of the reaction

Solution

Question 10

It increases the energy of the reactants

It decreases the energy of the products

It decreases the energy of the reactants

It does not change the enthalpy of the reactants

Solution

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