61. Choose the correct about Phenolphthalein as an indicator?
[A] It turns red in acids and yellow in bases
[B] It turns colourless in acids and pink in bases
[C] It turns orange in acids and brown in bases
[D] It turns colourless in acids and green in bases
Show Answer
Correct Answer: B [It turns colourless in acids and pink in bases]
Notes:
Phenolphthalein is a weak acid that is commonly used as an indicator. It is colourless in acids and pink in bases.
62. What do we call the device which uses electrical energy to carry non-spontaneous chemical reactions?
[A] Voltaic cell
[B] Galvanic cell
[C] Daniel cell
[D] Electrolytic cell
Show Answer
Correct Answer: D [Electrolytic cell]
Notes:
An electrolytic cell is an electrochemical cell which uses electrical energy to drive a non-spontaneous redox reaction.
63. Where does the oxidation takes place in a Galvanic cell?
[A] Anode
[B] Cathode
[C] Oxidation does not take place
[D] None of the above
Show Answer
Correct Answer: A [Anode]
Notes:
In a galvanic cell, the half-cell in which oxidation takes place is called anode and it has a negative potential with respect to the solution. The other half-cell in which reduction takes place is called cathode and it has a positive potential with respect to the solution.
64. Which of the following is the formula of cell constant?
[A] length/2 x Area
[B] length/Area
[C] 2 x length/Area
[D] length x Area
Show Answer
Correct Answer: B [length/Area]
Notes:
The quantity length/Area is called cell constant denoted by the symbol, G*. The cell constant is usually determined by measuring the resistance of the cell containing a solution whose conductivity is already known.
65. What is the S.I unit of Molar conductivity?
[A] S m3 mol-2
[B] S m2 mol-2
[C] S m-1 mol2
[D] S m2 mol-1
Show Answer
Correct Answer: D [S m2 mol-1]
Notes:
If conductivity(κ) of the solution is expressed in S m2 and the concentration(c) is expressed in mol m-3, then the units of Molar conductivity are expressed in S m2 mol-1.
66. What do we call the molar conductivity when the concentration approaches zero?
[A] Reacting molar conductivity
[B] Zero level molar conductivity
[C] Limiting molar conductivity
[D] Ideal molar conductivity
Show Answer
Correct Answer: C [Limiting molar conductivity]
Notes:
When concentration approaches zero, the molar conductivity is known as limiting molar conductivity.
67. Which of the following is not a weak electrolyte?
[A] Acetic acid
[B] Carbonic acid
[C] Potassium Hydroxide
[D] All of the above
Show Answer
Correct Answer: C [Potassium Hydroxide]
Notes:
An electrolyte that does not completely dissociate in aqueous solution is known as weak electrolyte. For example: acetic acid, carbonic acid etc. Potassium Hydroxide is a strong electrolyte.
68. As per Faraday’s Laws of Electrolysis, the amount of chemical reaction which occurs at any electrode during electrolysis proportional to which of the following?
[A] the concentration of electrolyte
[B] length of the electrode
[C] quantity of electricity passed through the electrolyte
[D] All of the above
Show Answer
Correct Answer: C [quantity of electricity passed through the electrolyte]
Notes:
As per Faraday’s 1st Law of Electrolysis, the amount of chemical reaction which occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte (solution or melt).
69. What is the reason for the presence of the vast number of organic compounds in nature?
[A] Carbon exists in free state
[B] Catenation property of carbon
[C] Low atomic mass of carbon
[D] None of the above
Show Answer
Correct Answer: B [Catenation property of carbon]
Notes:
Because of the catenation property of carbon, vast number of organic compounds are present in nature. Catenation refers to the linkage of atoms of the same element into longer chains.
70. Choose the correct about Methane:
[A] It is an unsaturated hydrocarbon
[B] Refined liquid methane is used as a rocket fuel.
[C] Its chemical formula is C2H6
[D] All of the above
Show Answer
Correct Answer: B [Refined liquid methane is used as a rocket fuel.]
Notes:
Methane is a saturated hydrocarbon. Its chemical formula is CH4. It is the main constituent of natural gas. Also, refined liquid methane is used as a rocket fuel.
