Surface-Chemistry-Quiz-7

Surface Chemistry Quiz-7

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. Which of the following statements is incorrect?

•  Physical adsorption occurs at very low temperature and chemisorptions occur at all temperature
•  The magnitude of chemisorption decreases with rise in temperature and physisorption increases with rise in temperature
•  Chemisorption is irreversible and physisorption is reversible
•  In physisorption, the activation energy of desorption is very low and in chemisorption, the activation energy of desorption is very high

Solution
For chemisorption, high temperature is favourable. It increases with rise in temperature. On the other hand low temperature is favourable for physisorption so it decreases with rise in temperature

Q2.The example(s) of anionic surfactants is/are

•  
•  
•  
•  

Solution
is an anionic surfactants

Q3.  Efficiency of a catalyst depends on its:

•   Particle size
•  Solubility
•  Molecular weight
•  None of these

Solution
Larger is surface area, more is efficiency of catalyst. The surface area becomes more in finely powdered state, colloidal state or if surface is rough.

Q4. Medicines are more effective if they are used in :

•  Colloidal state
•  Solid state
•  Solution state
•  None of these

Solution
Colloidal state has large surface area and provides more effective adsorption of medicine to bring in better results.

Q5.Which among the following statements are correct with respect to adsorption of gases on a solid? (i)The extent of adsorption is equal toaccording to Freundlich isotherm.

(ii)The extent of adsorption is equal toaccording to Freundlich isotherm.

(iii)The extent of adsorption is equal to (1+bp)/ap according to Langmuir isotherm. (iv) The extent of adsorption is equal to ap/(1+bp)according to Langmuir isotherm. (v)Freundlich adsorption isotherm fails at low pressure, where , and are constant and is pressure

•  (i) and (iii)
•  (i) and (iv)
•  (ii) and (iii)
•  (ii) and (iv)

Solution
 Extent of adsorption= (Freundlich adsorption isotherm) The amount of gas adsorbed does not increase as rapidly as the pressure. The extent of adsorption=ap/(1+bp) (Langmuir adsorption isotherm) Where k,a,b, are constants and p is pressure. 

Q6. Gold number :

•  May be defined as the milligram of the dry material of which the hydrophilic sol is prepared and which when added to 10 mL of red gold sol, will prevent it from coagulation on the addition of 1 mL of 10 per cent sodium chloride solution
• May be defined as the milligram of the dry material of which the hydrophilic sol is prepared and which when added to 1 mL of red gold sol will prevent it from coagulation on the addition of 10 mL of 10 per cent sodium chloride solution
• May be defined as the milligram of the dry material of which the hydrophilic sol is prepared and which when added to 1 mL of red gold sol will prevent it from coagulation on the addition of 1 mL of 1 per cent sodium chloride solution
•  None of the above

Solution
Gold no.is the amount of lyophilic in mg which just protect 10 mL gold sol against coagulation by 1 mL of 10% NaCl solution. It is a measure of protective power of lyophilic colloids.

Q7.Which is not a colloidal solution of gas in liquid?

•  Froths
•  Foams with tiny bubbles
•  Mist
•  Whipped cream

Solution
Mist is liquid dispersed in gas.

Q8.The coagulating power of an electrolyte for arsenioussulphide decreases in order

•  
•  
•  
•  

Solution
Coagulating power of an electrolyte for arsenioussulphide decreases as

Q9.Which reaction characteristics are changing by the addition of a catalyst to a reaction at constant

temperature? (i)activation energy (ii)Equilibrium constant (iii)Reaction entropy (iv)Reaction enthalpy

•  (i) only
•  (iii) only
•  (i) and (ii) only
•  All of these

Solution
Catalyst affects only activation energy. It brings down activation energy of reaction. Catalyst does not affect equilibrium constant, reaction entropy and reaction enthalpy.

Q10. During hydrogenation of oils, catalyst commonly used is :

•  
•  Finely divided Ni
•  Fe
• 

Solution