Surface-Chemistry-Quiz-9

Surface Chemistry Quiz-9

Dear Readers,

The one subject in NEET which is candidates who can easily attain good marks is Chemistry. That's the reason, often, one doesn’t pay notice and choose to compromise it. But if one wants to rank above others, the tip is to be thorough with NEET chemistry concepts. The understanding of reactions and definite basic understanding is what requires major attention in Chemistry but once done it only gets simpler from there. The main focus on the to-do list should be on getting a hang of the NCERT syllabus of NEET chemistry..

Q1. Alum purify muddy water by

•  Dialysis
•  Adsorption
•  Coagulation
•  Forming a true solution

Solution
Alum purify muddy water y coagulation.

Q2.The reaction rate at a given temperature is slower when :

•  The energy of activation is higher
•  The energy of activation is lower
•  Entropy changes
•  Initial concentration of the reactants remains constant

Solution

Q3.  A catalyst in the finely divided form is most effective because :

•   Less surface area is available
•  More active centres are formed
•  More energy gets stored in the catalyst
•  None of the above

Solution
Catalyst in finely powdered state possesses larger surface area and more active centres and thus,becomes more effective.

Q4. Which one of the following statements is incorrect?

•  Adsorption always leads to a decrease in enthalpy and entropy of the system
•  Adsorption arises due to unsaturation of valence forces of atoms or molecules on the surface
•  Adsorption increases with rise in the temperature
•  Adsorption decreases the surface energy

Solution
When temperature increases, the adsorbed molecules get energy and desorption starts increasing, therefore adsorption decreases with increase in temperature

Q5.Cellulose dispersed in ethanol is called

•  Emulsion
•  Collodion
•  Micelle
•  Hydrophilic sol

Solution
 Cellulose dispersed in ethanol is called collodion.

Q6. From the following which is not an emulsifier?

•  Agar
•  Milk
• Gum
•  Soap

Solution
The substances that stabilise emulsions are called emulsifiers. Agar, gum and soap all were emulsifier while milk is an emulsion, not an emulsifier.

Q7.Which characteristic of adsorption is wrong?

•  Physical adsorption in general decreases with temperature
•  Physical adsorption in general increases with temperature
•  Physical adsorption is a reversible process
•  Adsorption is limited to the surface only

Solution
Physical adsorption is non-directional, reversible,multilayers exothermic process where adsorbent molecules are held on surface of adsorbent by physical forces such as van der Waals’ forces

Q8.Mention the type of reaction to obtain Au(sol).

Reaction,

•  Hydrolysis
•  Oxidation
•  Reduction
•  Double decomposition

Solution
The gold sol is obtained by the reduction of.

                                                                      (Gold Sol)

Q9.Gold number of few colloids are given below, Gelatin = 0.005 Starch = 25 Egg albumin = 0.08 Gum Arabic = 0.10 Which is best protective colloid?

•  Gelatin
•  Starch
•  Egg albumin
•  Gum Arabic

Solution
Lower is the value of gold number, more is its protecting power.

Q10. Decomposition of urea intois followed by the action of enzyme :

•  Urease
•  Pepsin
•  Trypsin
• None of these

Solution