Question

Assertion: Rusting of Iron is quicker in saline water than in ordinary water.
Reason: Presence of $N{a^ + }$ and \[C{l^ - }\] ions increase the conductance of the saline water.
A. Both Assertion and Reason are true and Reason is correct explanation of Assertion
B. Both Assertion and Reason are true and Reason is not the correct explanation of Assertion
C. Assertion is true but Reason is false
D. Assertion is false but Reason is true
E. Both Assertion and Reason are false

Answer 1

Hint: Rusting of iron happens due to redox reactions.
There are few necessary conditions required for rusting of iron, like air, water or moisture.
We also know that conductance of any electrolyte is directly proportional to the number of ions present in the electrolyte.

Complete step by step answer:
Rusting of iron takes place in presence of few essential factors like air or oxygen, water or moisture, and it is reddish brown oxide on the surface of iron.
Rust is oxidation of Iron in the presence of air or moisture. The reaction can be written as:
\[4Fe + 3{O_2} + 2x{H_2}0 \to 2F{e_2}{O_3}.x{H_2}O\]
This product is a chemical formula of rust.
Now, we know that Fe is getting oxidised by giving 2 electrons as shown below in reaction:
\[Fe \to F{e^{ + 2}} + 2{e^ - }\]
This process is increased if there is presence of other ions in contact with the metal surface.
And we know that saline water has salt in it. So the presence of salt will give ions as below:
\[NaCl \to N{a^ + } + C{l^ - }\]
These ions increase the conductance of saline water and thus, these ions will come in contact with Fe surface and thus increase oxidation of iron.
If oxidation of iron is increased then rust formation is quicker, thus both assertion and reason are correct and reason is the correct explanation of assertion.

So, the correct answer is “Option A”.

Additional Information:
Rusting of iron is a redox reaction where iron is getting oxidised and Oxygen present in the atmosphere is getting reduced.

Note: We should be careful in stating whether the reason is the correct explanation of the assertion. We should also be careful instating whether oxidation and reduction has taken place of which substances.