25+ MCQ on Adsorption with Answers

MCQ on Adsorption: This is the phenomenon in which the concentration of a substance increases at the surface of a solid or liquid due to molecular surface forces. The substance that gets adsorbed on the surface is known as the adsorbate, which may be a gas, liquid, or solid. The material on which adsorption occurs is called the adsorbent. Common examples of adsorbents include activated charcoal, platinum (Pt), palladium (Pd), nickel (Ni), silica gel, gelatin, alumina (Al₂O₃), and starch. In contrast, absorption refers to the process in which a substance is uniformly distributed throughout the volume of another solid or liquid. When both adsorption and absorption occur simultaneously, the combined process is termed sorption.

The reason adsorption occurs lies in the difference between the surface and the bulk of the adsorbent. Inside the bulk, the particles are equally surrounded by neighboring particles, resulting in balanced intermolecular forces. However, at the surface, these particles lack neighboring molecules on all sides, leading to unbalanced or residual attractive forces. These forces are responsible for attracting and holding the adsorbate molecules onto the surface.

Depending on the nature of the forces between the adsorbate and adsorbent, adsorption is classified into two types: physical adsorption (involving weak van der Waals forces) and chemical adsorption (involving strong chemical bonds). Adsorption finds several practical applications. For instance, gas masks used in coal mines contain activated charcoal or a mixture of adsorbents to adsorb poisonous gases and ensure safe breathing. Animal charcoal is used to remove colored impurities from solutions by adsorption. Additionally, the separation of inert (noble) gases is possible by utilizing their differing degrees of adsorption on coconut charcoal at varying temperatures.

Here Below we have listed the top 25+ MCQ on Adsorption with Answers and Explanation. these MCQ are helpful for Prepaation of NEET Biology. Hee you can read NEET BIology MCQ

MCQ on Adsorption with Answers and Explanation

1.Physical adsorption is appreciable at__________
(1) Higher temperature
(2) Lower temperature
(3) At room temperature
(4) 1000°C
Answer: (2) Lower temperature
Explanation: Physical adsorption is exothermic. According to Le Chatelier’s principle, decreasing the temperature favors the forward (adsorption) process. Hence, it is more appreciable at lower temperatures.

Read: Digestion and Absorption

2. Which characteristic of adsorption is wrong___________
(1) Physical adsorption in general decreases with temperature
(2) Physical adsorption in general increases with temperature
(3) Physical Adsorption is a reversible process
(4) Adsorption is limited to the surface only
Answer: (2) Physical adsorption in general increases with temperature
Explanation: Since physical adsorption is exothermic, increasing temperature reduces adsorption. Therefore, this statement is incorrect.

Read: MCQ on Ecosystem with Answers PDF

3. The rate of physical adsorption________
(1) Decreases with increase of pressure
(2) Is independent at high pressure
(3) Is maximum at one atmospheric pressure
(4) Always increases with increase of pressure
Answer: (2) Is independent at high pressure
Explanation: Initially, adsorption increases with pressure, but at high pressure, saturation is reached, so further increase in pressure doesn’t affect the rate.

Read: MCQ on Pollution

4. Which of the following is not a characteristic of chemisorption__________
(1) Adsorption is irreversible
(2) DH is of the order of 40 kJ
(3) Adsorption is specific
(4) Adsorption increases with increase of surface area
Answer: (2) ∆H is of the order of 40 kJ
Explanation: Chemisorption has much higher enthalpy changes (80–200 kJ/mol). 40 kJ/mol is typical for physical adsorption, not chemisorption.

5. Sorption is the term used when_______
(1) Adsorption takes place
(2) Absorption takes place
(3) Both takes place
(4) Desorption takes place
Answer: (3) Both takes place
Explanation: Sorption is a general term that includes both adsorption (surface-based) and absorption (bulk-based)

6. Which among the following statement is false_________
(1) The adsorption may be monolayered or multilayered
(2) Particle size of adsorbent will not affect the amount of adsorption
(3) Increase of pressure increases amount of adsorption
(4) Increase of temperature may decrease the amount of adsorption
Answer: (2) Particle size of adsorbent will not affect the amount of adsorption
Explanation: Smaller particle size increases surface area, thereby increasing adsorption. So this statement is false.

7. Which of the following is not an adsorbent?
(1) Carbon
(2) Polymers and resins
(3) Clay
(4) Dry sponge
Answer: (4) Dry sponge
Explanation: A dry sponge absorbs liquid inside its pores (bulk phenomenon), not surface adsorption.

8. The extent of adsorption of a gas on a solid depend on___________
(1) nature of gas
(2) pressure of gas
(3) temperature of the system
(4 )all of the mentioned
Answer: (4) All of the mentioned
Explanation: Adsorption depends on nature of gas, pressure, and temperature.

9. In physical adsorption, the gas molecules are held on solid surface by_________
(1) Chemical forces
(2) Electrostatic forces
(3) Gravitational forces
(4) Vander Waal’s forces
Answer: (4) Van der Waals forces
Explanation: Physical adsorption occurs due to weak Van der Waals forces, unlike chemisorption which involves strong chemical bonds.

10. Which one of the following is an example of adsorption?
(1) ammonia in contact with water
(2) anhydrous CaCl2 with water
(3) silica gel in contact with water vapours
(4) all of these
Answer: (3) Silica gel in contact with water vapours
Explanation: Water vapors get adsorbed on silica gel’s surface. Other examples involve absorption.

11. Which of the following isotherm is applicable to physical adsorption?
(1) Langmuir
(2) BET
(3) Freundlich
(4) Kisluik
Answer: (3) Freundlich
Explanation: Freundlich isotherm describes multilayer physical adsorption on heterogeneous surfaces.

12. Chemisorption__________
(1) Involves the weak attractive interactions between adsorbent and adsorbate
(2) Is irreversible in nature
(3) Decreases with increase of temperature
(4) Involves multilayer formation of adsorbent on adsorbate
Answer: (2) Is irreversible in nature
Explanation: Chemisorption forms strong chemical bonds and is usually irreversible and specific.

13. Which of the following statements regarding the physical adsorption of a gas on surface of solid is not correct?
(1) on increasing temperature, adsorption increases continuously
(2) enthalpy changes are negative
(3) adsorption is specific
(4) it is reversible in nature
Answer: (1) On increasing temperature, adsorption increases continuously
Explanation: Adsorption decreases with rising temperature for physical adsorption. Hence, this statement is incorrect.

14. Pd can adsorb 900 times its volume of hydrogen. This is called __
(1) Absorption
(2) Adsorption
(3) Occlusion
(4) 2 & 3 both
Answer: (4) 2 & 3 both
Explanation: Palladium adsorbs hydrogen on its surface and also allows it to diffuse into the bulk, called occlusion. So both terms apply.

15. Which is correct________
(1) Langmuir adsorption is highly specific
(2) vander-Waal’s adsorption is reversible
(3) Both 1 & 2 are exothermic
(4) All are correct
Answer: (4) All are correct
Explanation:
Langmuir is highly specific
van der Waals adsorption is reversible
Both adsorption types are exothermic

16. Adsorption is accompanied by________
(1) Decrease in entropy of the system
(2) Decrease in enthalpy of the system
(3) TDS for the process is negative
(4) All
Answer: (4) All
Explanation:
Entropy decreases (less randomness)
Enthalpy decreases (exothermic)
T∆S is negative, so Gibbs free energy (∆G) is negative

17. Which one of the following is not a correct statement ?
(1) Physical adsorption is reversible in nature
(2) Physical adsorption involves vander waals forces
(3) Rate of physical adsorption increases with increase of pressure on the adsorbate
(4) High activation energy is involved for physical adsorption
Answer: (4) High activation energy is involved for physical adsorption
Explanation: Physical adsorption involves low activation energy. Chemisorption requires high energy.

18. The extent of adsorption of a gas on a solid depends on_______
(1) The nature of gas
(2) Pressure of gas
(3) Temperature of the system
(4) All
Answer: (4) All
Explanation: The nature of gas, pressure, and temperature all affect adsorption extent.

19. Which forms multi molecular layers during adsorption________
(1) Physical adsorption
(2) vader Waal’s adsorption
(3) Freundlich adsorption
(4) All
Answer: (4) All
Explanation: All mentioned forms can lead to multilayer adsorption, especially in physical adsorption.

20. The Langmuir adsorption isotherm is deduced using the assumption.
(1) The adsorption sites are equivalent in their ability to adsorb the particles.
(2) The heat of adsorption varies with coverage
(3) The adsorption molecules interact with each other.
(4) The adsorption takes place in multilayers
Answer: (1) The adsorption sites are equivalent in their ability to adsorb the particles.
Explanation: Langmuir isotherm assumes homogeneous surface and monolayer adsorption with no interaction between molecules.

21. Which of the following is incorrect for physi-sorption_________
(1) Reversible
(2) Increases with increase in temperature
(3) Low heat of adsorption
(4) Increases with increase in surface area
Answer: (2) Increases with increase in temperature
Explanation: Being exothermic, physiosorption decreases with temperature rise. So this is incorrect.

22. In Freundlich Adsorption isotherm, the value of 1/n is__________
(1) 1 in case of physical adsorption
(2) 1 in case of chemisorption
(3) between 0 and 1 in all cases
(4) between 2 and 4 in all cases
Answer: (3) Between 0 and 1 in all cases
Explanation: This condition ensures that adsorption increases with pressure, but the increase is less at high pressures (non-linear relation).

Mcq on adsorption with answers, Mcq on adsorption with answers pdf, Mcq on adsorption class 12, Mcq on adsorption pdf, Mcq on adsorption class 11, Adsorption and Colloids Class 11 MCQ, MCQ on adsorption isotherm, Surface Chemistry MCQ with answers PDF, MCQ on Adsorption PDF