Surface Chemistry
204 Questions
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2003
Q201
JEE Mains
MCQ
14 Mar 2026
Which one of the following characteristics is not correct for physical adsorption?
A.
Adsorption increases with increase in temperature
B.
Adsorption is spontaneous
C.
Both enthalpy and entropy of adsorption are negative
D.
Adsorption on solids is reversible
2003
Q202
JEE Advanced
Numerical
14 Mar 2026
1 gm of charcoal adsorbs 100 ml 0.5 M CH3COOH to form a monolayer, and thereby the molarity of CH3COOH reduces to 0.49. Calculate the surface area of the charcoal adsorbed by each molecule of acetic acid. Surface area of charcoal = 3.01 $\times$ 102 m2/gm.
Correct Answer: 5 $$\times$$ 10<sup>-19</sup> m<sup>2</sup>
Explanation:
The number of moles of acetic acid in 100 mL (before adding charcoal) = 0.05 mol
The number of moles of acetic acid in 100 mL (after adding charcoal) = 0.049 mol
The number of moles of acetic acid adsorbed on the surface of charcoal = 0.05 - 0.049 = 0.001 mol
The number of molecules of acetic acid adsorbed on the surface of charcoal = 0.001 $\times$ 6.02 $\times$ 1023 = 6.02 $\times$ 1020
Given that the surface area of charcoal = 3.01 $\times$ 102
m2
, so the area occupied by single acetic acid molecule on the
surface of charcoal is
= ${{3.01 \times {{10}^2}} \over {6.02 \times {{10}^{20}}}}$ = 5 $\times$ 10-19 m2
2002
Q203
JEE Mains
MCQ
14 Mar 2026
The formation of gas at the surface of tungsten due to adsorption is the reaction of order :
A.
0
B.
1
C.
2
D.
insufficient data
2002
Q204
JEE Mains
MCQ
14 Mar 2026
Alum helps in purifying water by :
A.
forming Si complex with clay particles
B.
sulphate part which combines with the dirt and removes it
C.
coagulating the mud particles
D.
making mud water soluble