Surface Chemistry Quiz-15

Surface Chemistry Quiz-15

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.  On adding 1 mL of solution of 10% NaCl to 10mL of gold sol in the presence of 0.25g of starch, the coagulation is just prevented. The gold number of starch is

•   0.25
•   0.025
•   2.5
•   250

Solution
Gold number is the number of milligrams of a hydrophilic colloid that will just prevent the coagulation of 10 mL of a gold sol on addition of 1 mL of 10% NaCl solution.
∴ Gold number =0.25×1000=250

Q2.  Which of the following is not a surfactant :

•  
  
  
•   CH₂(CH₂)₂14 CH₂NH₂
•  
•   Decyl pyridinium chloride

Solution
Rest all have moities with polar and non-polar part.

Q3.  Lyophilic sols are more stable than lyophobic sols because :

•   The colloidal particles have positive charge
•   The colloidal particles have no charge
•   The colloidal particles are solvated
•   There are strong electrostatic repulsions between the negatively charged colloidal particles

Solution
Lyophilic possesses solvent loving nature and thus, a thin layer of dispersed phase is formed around sol particles.

Q4.  In temporary poisoning, catalytic poisons act by :

•   Coagulating the catalyst
•   Chemically combining with any one of the reactants
•   Chemically combining with the catalyst
•   Getting physically adsorbed on the active centres of the catalyst

Solution
Poisoners are adsorbed on active centres either physically (temporary poisoning) or chemically (permanent poisoning).

Q5. Which is not correct for catalyst? It :

•   Enhances the rate of reaction in both directions
•   Changes enthalpy of reaction
•   Reduces activation energy of reaction
•   Specific in nature

Solution
  Catalyst does not make the reaction more exothermic or endothermic.

Q6.  Soap removes grease by :

•   Adsorption
•   Emulsification
•   Coagulation
•   None of these

Solution
Soap solutions act as emulsifier to remove grease via emulsification of grease in water.

Q7. Which acts as a promoter for nickel in the hydrogenation of oils?

•   Cu
•   Mo
•   Fe
•   Pt

Solution

Q8. Identify the correct statements regarding enzymes.

•   Enzymes are specific biological catalysts that can normally function at very high temperatures (T ~ 1000 K)
•   Enzymes are normally heterogeneous catalysts that are very specific in their action.
•   Enzyme are specific biological catalysts that cannot be poisoned
•   Enzyme are specific biological catalysts that possess well defined active sites

Solution
Normal optimum temperature of enzymes is between 25℃ to 40℃ hence (a) is false. Similarly, (b) and (c) are also false. Enzymes have well defined active sites and their actions are specific in nature.

Q9. Mutarotation of glucose is an example of :

•   Acid-base catalysis
•   Homogeneous catalysis
•   Both (a) and (b)
•   None of these

Solution
The reaction in solution phase (P=1) is catalysed by H⁺.

Q10.  Which one of the following methods is commonly used for destruction of colloid?

•   Dialysis
•   Condensation
•   Filtration by animal membrane
•   By adding electrolyte

Solution
Addition of electrolyte brings in coagulation of sol.