Engineering Chemistry MCQ (B.E.T. Adsorption Isotherm)

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Engineering Chemistry MCQ (B.E.T. Adsorption Isotherm)

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1. The B.E.T. theory was proposed in the year?
a) 1940
b) 1935
c) 1938
d) 1945
Answer: c
Explanation: Brunauer, Emmett and Teller proposed a theory in 1938 which is known as B.E.T. theory.

2. The B.E.T. theory was based on the ____________
a) Single layer adsorption
b) Multilayer adsorption
c) Double layer adsorption
d) None of the mentioned
Answer: b
Explanation: The B.E.T. theory was based on the multilayer adsorption. It aims to explain the physical adsorption of gas molecules on a solid surface and serves as
the basis for an important analysis technique for the measurement of the specific surface area of a material.

3. Which of the following is an assumption for B.E.T theory?
a) The solid surface possess uniform, localised sites
b) The adsorption at one site does not affect adsorption at neighbouring site
c) Physical adsorption of adsorbate occurs resulting in the formation of multilayers
d) All of the mentioned
Answer: d
Explanation: The assumptions for B.E.T theory are – the solid surface possess
uniform, localised sites, the adsorption at one site does not affect adsorption at
neighbouring site and physical adsorption of adsorbate occurs resulting in
formation of multilayers, etc.

4. The energy of adsorption in the first layer is ____________
a) Increasing
b) Decreasing
c) Constant
d) None of the mentioned
Answer: c
Explanation: The energy of adsorption in the first layer is constant. It aims to explain
the physical adsorption of gas molecules on a solid surface and serves as the basis
for an important analysis technique for the measurement of the specific surface
area of a material.

5. The surface area available for the nth layer is equal to the coverage of ____________
a) (n-1)th layer
b) (n+1)th layer
c) nth layer
d) none of the mentioned
Answer: a
Explanation: The surface area available for the nth layer is equal to the coverage of
(n-1)th layer. By application of the BET theory, it is possible to determine the inner surface of hardened cement paste.

6. In the B.E.T. equation, what does p0 denotes?
a) Pressure of the gas molecules
b) Unsaturated vapor pressure of the gas molecules
c) Saturated vapor pressure of the gas molecules
d) All of the mentioned
Answer: c
Explanation: In the B.E.T. equation, p0 denotes the saturated vapour pressure of the gas molecules at the same temperature.

7. According to B.E.T. equation, the plot of P/V(P0-P) versus P/P0 will yield a ____________
a) Straight line
b) Parabola
c) Hyperbola
d) Eclipse
Answer: a
Explanation: According to B.E.T. equation, the plot of P/V(P0-P) versus P/P0 will yield a
straight line. By application of the BET theory, it is possible to determine the inner surface of hardened cement paste.

8. The B.E.T. theory is used in calculating the ____________
a) Surface area of adsorbate
b) Surface area of adsorbent only
c) Surface area of adsorbents and catalyst
d) None of the mentioned
Answer: c
Explanation: The B.E.T. theory is used in calculating the surface area of adsorbents
and catalyst. By application of the BET theory, it is possible to determine the inner
surface of hardened cement paste.

9. The surface area occupied by a single gas molecule is inversely proportional to the ____________
a) Molar mass of the gas adsorbed
b) Density of the liquefied gas
c) Volume of the gas
d) All of the mentioned
Answer: b
Explanation: The surface area occupied by a single gas molecule is inversely
proportional to the density of the liquefied gas. Porous inorganic materials such as
mesoporous silica and layered clay minerals have high surface areas of several hundred m2g−1 calculated by the BET method.

10. The total surface area covered by all the molecules of the adsorbed gas is given by ____________
a) S = nβ/NA
b) S = βNA/n
c) S = nβNA
d) S = NA/nβ
Answer: c
Explanation: The total surface area covered by all the molecules of the adsorbed gas
is given by S = nβNA. The surface area occupied by a single gas molecule is inversely
proportional to the density of the liquefied gas.