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#### Surface Chemistry Two Marks Question

12th Standard EM

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Chemistry

Time : 00:30:00 Hrs
Total Marks : 18
9 x 2 = 18
1. Give two important characteristics of physiscorption

2. Differentiate physisorption and chemisorption

3. In case of chemisorption, why adsorption first increases and then decreases with temperature?

4. Which will be adsorbed more readily on the surface of charcoal and why; NH3 or CO2?

5. Heat of adsorption is greater for chemisorptions than physisorption. Why?

6. In a coagulation experiment 10 mL of a colloid (X) is mixed with distilled water and 0.1M solution of an electrolyte AB so that the volume is 20 mL. It was found that all solutions containing more than 6.6 mL of AB coagulate with in 5 minutes. What is the flocculation values of AB for sol (X)?

7. The mechanism of Fridel crafts reaction is given below
${ C }_{ 6 }{ H }_{ 5 }+{ { CH }_{ 3 }Cl\overset { anhydrous\\ \quad \quad \quad { Alcl }_{ 3 } }{ \longrightarrow } }{ C }_{ 6 }{ H }_{ 5 }{ CH }_{ 3 }+HCl$

8. Thermal decomposition of KClO in presence of MnO2 proceeds as follows.
Steps in the reaction 2KClO → 2KCl+3Ocan be given as

9. Formation of water due to the reaction of H2 and O2 in the presence of Cu can be given as