Question

Given below are two statements: Statement I: The electrical conductivity of a solution decreases with dilution. Statement II: The overall reaction in $H_{2}-O_{2}$ fuel cell is: $2H_{2}O(l)\longrightarrow2H_{2}(g)+O_{2}(g)$. The correct answer is:

• A. Both statements I and statement II are correct.
• B. Both statements I and statement II are not correct.
• C. Statement I is correct but statement II is not correct.
• D. Statement I is not correct but statement II is correct.

Hint:

Conductivity ($\kappa$) ALWAYS decreases with dilution because ion density drops, but molar conductivity ($\Lambda_{m}$) ALWAYS increases with dilution.

Answer 1

The Correct Option is C

Step 1: Read the two statements.
Statement I says conductivity of a solution decreases on dilution. Statement II gives the overall reaction of a hydrogen-oxygen fuel cell. We judge each.

Step 2: Understand conductivity.
Conductivity is the current-carrying power per unit volume. It depends on how many ions are present in each unit of volume.

Step 3: Check statement I.
When we add more water, the same ions spread out into a larger volume, so the number of ions per unit volume falls. This lowers the conductivity. So statement I is correct.

Step 4: Recall the fuel cell reaction.
In a hydrogen-oxygen fuel cell, the gases combine to make liquid water and produce electricity. \[ 2H_2(g) + O_2(g) \longrightarrow 2H_2O(l) \]

Step 5: Check statement II.
The statement writes the reaction the other way round, which is actually the electrolysis of water, not the fuel cell. So statement II is wrong.

Step 6: Combine the results.
Statement I is correct but statement II is not correct. \[ \boxed{\text{I correct, II not correct}} \]