Tag: chemical reactions

Quizzes (8) Questions (144)

Questions Related to chemical reactions

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

We can expect that pure water:

  1. will not normally conduct electricity

  2. will normally conduct electricity

  3. slightly conduct electricity

  4. completely conduct electricity
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Water has very low ionisation constant so it dissociates very low and pure water  consists almost entirely of molecules; as no of ions are very less in pure water so normally it will not conduct electricity.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Which modifications are necessary to determine the resistance of solution by the usual method of measurements on Wheatstone's bridge principle?

  1. A.C. should be used

  2. A conductivity cell is used

  3. Galvanometer is replaced by magic eye or headphone arrangement

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

All of the following modifications are necessary to determine the resistance of solution by the usual method of measurements on Wheatstone's bridge principle.


(A) A.C. should be used.
(B) A conductivity cell is used.
(C) The galvanometer is replaced by magic eye or headphone arrangement.

If D.C. is used, electrolyte solution will go electrolysis and the change in concentration during the passage of current will not allow reaching the steady value of the null point. In A.C. galvanometer does not work. Also to put the solution at one end in the gap of the meter bridge, a conductivity cell is needed.

Hence, the correct option is $D$

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry
Assertion: Nickel is a metal and it conducts electricity through its valence shell electrons.
Reason: Nickel sulphate solution conducts electricity through its ions.

  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion

  2. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

  3. Assertion is true but Reason is false

  4. Assertion is false but Reason is true

  5. Both Assertion and Reason are false
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nickel is a metal and it conducts electricity through its valence shell electrons while nickel sulphate solution conducts electricity through its ions (formed by dissociation of nickel sulphate solutions).

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

A solution of sodium in liquid ammonia at $-33^oC$ conducts electricity. On cooling, the conductivity of this solution _______.

  1. decreases

  2. increases

  3. remains same

  4. becomes 0
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A solution of sodium in liquid ammonia at $-33^oC$ conducts electricity. On cooling, the conductivity of this solution ...... The conductivity of the solution is due to presence of ammoniated electrons. With decrease in the temperature, the mobility of ammoniated electrons decreases due to which the electrical conductivity decreases.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Examine the following statement sand select the correct option.
A : Electrolytic conduction is a physical change.
B : In Electrolytic conduction, positive as well as negative ions conduct electricity.

  1. Both A and B are true

  2. Both A and B are false

  3. A is true and B is false

  4. A is false but B is true
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Electrolytic conduction is a chemical change. It involves a redox reaction.
In electrolytic conduction, positive as well as negative ions conduct electricity.
For example, during electrolysis of molten NaCl, both $Na^+$ and $Cl^-$ ions are involved in the conduction of electricity.
Thus, A is false but B is true.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry
Assertion: In electrolysis of water, ions are not discharged at electrodes.
Reason: The current-carrying ions in an electrolytic cell are not necessarily discharged at the electrodes.

  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion

  2. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

  3. Assertion is true but Reason is false

  4. Assertion is false but Reason is true

  5. Both Assertion and Reason are false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The current-carrying ions in an electrolytic cell are not necessarily discharged at the electrodes. This is true for the electrolysis of aqueous salt solutions in which water is involved in the electrode reactions and not the current carrying ions.
$2H _2O \rightarrow O _2 + 4H^+ +4e^-$    oxidation
$2H _2O + 2e^- \rightarrow H _2 +2OH^-$   reduction

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry
Assertion: Electrolytic conductance increases with the increase of temperature
Reason: Metallic conductance decreases with the increase in temperature.

Choose the correct option.

  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion

  2. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

  3. Assertion is true but Reason is false

  4. Assertion is false but Reason is true

  5. Both Assertion and Reason are false
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The conductivity of an electrolyte depends on the temperature. With an increase in temperature, the conductivity of an electrolyte increases.This is due to increase in ionic mobility. 


For metals, the thermal conductivity is mainly a function of the motion of free electrons. As the temperature increases, the molecular vibrations increase (in turn increasing the mean free path of molecules). So, they obstruct the flow of free electrons, thus reducing the conductivity.