Daily Olympiad: Chemistry - Surface Chemistry [20260511]

Challenge yourself with today's JEE Main practice! This test covers 'Surface Chemistry' for Chemistry (JEE Main - 11). Level: Hard | Duration: 45 mins.

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1. Which of the following is correct regarding physical adsorption?

Solution
Correct: D
Physical adsorption is exothermic as gas molecules are condensed on the surface, reducing randomness (ΔS < 0). The process becomes less favorable at higher temperatures.

2. The Langmuir adsorption isotherm assumes that:

Solution
Correct: D
Langmuir's model is based on the concept of a monomolecular layer of adsorbed gas, assuming uniform surface and no interaction between adsorbed molecules.

3. Which of the following factors does NOT affect the rate of physisorption?

Solution
Correct: D
Chemically inert gases show weak adsorption but are still affected by other factors like temperature and pressure. The adsorbent's surface nature also plays a role.

4. The critical micelle concentration (CMC) of a surfactant decreases as:

Solution
Correct: C
Longer hydrophobic chains stabilize micelles at lower concentrations, reducing the CMC. Temperature and ionic strength have inverse effects.

5. Which of the following is NOT a method for coagulating a colloidal sol?

Solution
Correct: D
Peptizing agents stabilize colloids rather than coagulate them. Coagulation occurs via neutralization of charge, heating, or mixing oppositely charged colloids.

6. The gold number of a protective colloid is defined as:

Solution
Correct: A
Gold number quantifies the protective power of colloids by determining how much is needed to prevent coagulation of a gold sol system.

7. Which of the following catalysts is most suitable for the Haber process?

Solution
Correct: A
Iron acts as the main catalyst, while molybdenum acts as a promoter to enhance its activity in the Haber process (N₂ + 3H₂ → 2NH₃).

8. Which of the following phenomena does NOT involve colloid chemistry?

Solution
Correct: D
Fermentation is a biochemical process involving enzymes (proteins in solution), not colloidal systems.