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Which of the following statements is/are...

Which of the following statements is/are not correct?
Adsorption is accompanied by decrease in enthalpy as well as decrease in entropy of the system.
Gases, which can react strongly with adsorbent show chemisorption.
When the value of the slope of the Freundlich isotherm is non-zero, adsorption is independent of pressure.
Gold number of potato starch is 0.15

A

A,D

B

B,C

C

A,C

D

C,D

Text Solution

Verified by Experts

The correct Answer is:
D
(A) Adsorption is accompained by decrease in enthalpy as well as in entropy of the system
` Delta G = delta H - T Delta S ` and adsorption is an exothermic process [thus has ` Delta H = (-) ` ve , i.e. decrases because after adsorption free movement is restricted , but to make the ` Delta G(-) ve , Delta H gt T. Delta S ` . Hence , the statement (A) is correct .
(B) Gases , which can react strongly with adsorbent show chemisorption as they form chemical bonds with the adsorbent . Hence, the statement (c) is also correct .
(C) When the value of slope of the Freundlich isotherm is non=zero , adsorption of a gas depends on pressure over it , till the adsorption is possible . According to Freundlich isotherm equation :
` (x)/(m) = k. p^(1//n)`
where ,
x = mass of gas adsorbed,
m = mass of adsorbent,
p = pressure ,
k = constant,
n = integer number,
Hence, statement (C) is not correct .
(D) Gold number is defined as, '' The number of milligrams of a hydrophilic colloid that will just prevet the precipitation of 10 mL of a gold sol on the addition of 1 mL of 10% sodium chloride solution'' . Gold number for patato starch is 20 .
Hence , statements (C) and (D) are not correct and therefore (d) is the correct option .
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Knowledge Check

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    A
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    B
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    C
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