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Surface Chemistry

NEET Chemistry · 98 questions · Page 2 of 10 · Click an option or "Show Solution" to reveal answer

Q11
Which property of colloidal solution is independent of charge on the colloidal particles?
A Electro-osmosis
B Tyndall effect
C Coagulation
D Electrophoresis
Correct Answer
Option B
Solution

Tyndall effect is the scattering of light by sol particles which cannot be affected by charge on them.

Q12
Which property of colloids is not dependent on the charge on colloidal particles?
A Coagulation
B Electrophoresis
C Electro-osmosis
D Tyndall effect
Correct Answer
Option D
Solution

Tyndall effect is due to the scattering of light by colloidal particles and not due to the charge.

Q13
The protecting power of lyophilic colloidal sol is expressed in terms of
A coagulation value
B gold number
C critical micelle concentration
D oxidation number
Correct Answer
Option B
Solution

The lyophobic sols are less stable than lyophilic sols.

The lyophilic sols are thus used to protect the lyophobic sols.

This property of lyophilic sols is known as protective action of lyophilic sols.

Which can be represented by gold number.

Lesser the gold number, higher is the protecting power.

Q14
Which one of the following statements is incorrect about enzyme catalysis?
A Enzymes are mostly proteinous in nature.
B Enzyme action is specific.
C Enzymes are denatured by ultraviolet rays and at high temperature.
D enzymes are least reactive at optimum temperature.
Correct Answer
Option D
Solution

Enzymes are most reactive at optimum temperature. The optimum temperature for enzyme activity lies between 40°C to 60°C.

Q15
In Freundlich adsorption isotherm, the value of 1/n is
A between 0 and 1 in all cases
B between 2 and 4 in all cases
C 1 in case of physical absorption
D 1 in case of chemisorption.
Correct Answer
Option A
Solution

Freundlich adsorption isotherm:

xm=k.p1n{x \over m} = k.{p^{{1 \over n}}}

Where

xm{x \over m}

is the ratio of amount of adsorbent to the amount of adsorbate.

The value of n is always greater than 1.

So, the value of

1n{{1 \over n}}

lies between 0 and 1 in all cases.

Q16
If x is amount of adsorbate and m is amount of adsorbent, which of the following relations is not related to adsorption process?
A x/m = ff(p) at constant T
B x/m = f(T) at constant p
C p = f(T) at constant (x/m)
D xm=p×T{x \over m} = p \times T
Correct Answer
Option D
Solution
xm=p×T{x \over m} = p \times T

is incorrect.

Q17
The Langmuir adsorption isotherm is deduced using the assumption
A the adsorption sites are equivalent in their ability to adsorb the particles
B the heat of adsorption varies with coverage
C the adsorbed molecules interact with each other
D the adsorption takes place in multilayers.
Correct Answer
Option A
Solution

Langmuir adsorption isotherm is based on the assumption that every adsorption site is equivalent and that the ability of a particle to bind there is independent of whether nearby sites are occupied or not occupied.

Q18
A plot of log(x/m) versus log p for the adsorption of a gas on a solid gives a straight line with slope equal to
A log K
B −- log K
C n
D 1/n
Correct Answer
Option D
Solution

According to Freundlich adsorption isotherm, in the median range of pressure

xm∝P1n{x \over m} \propto {P^{{1 \over n}}}

⇒\Rightarrow

xm{x \over m}

= kP

1n^{{1 \over n}}

taking log both sides, we get, log

xm{x \over m}

= logk +

1n{1 \over n}

logP Here in graph between log

xm{x \over m}

and logP, slope is

1n{1 \over n}

and intercepts = log k.

Q19
Which one of the following forms micelles in aqueous solution above certain concentration?
A Dodecyl trimethyl ammonium chloride
B Glucose
C Urea
D Pyridinium chloride
Correct Answer
Option A
Solution

Dodecyl trimethyl ammonium chloride is a cationic surfactant and forms micelles in aqueous solution above critical micelle concentration (CMC).

Q20
The enzyme which hydrolyses triglycerides to fatty acids and glycerol is called
A maltase
B lipase
C zymase
D pepsin
Correct Answer
Option B
Solution

Triglycerides are lipids, hence these are hydrolysed by lipases to glycerol and fatty acids.

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