1
COMEDK 2024 Evening Shift
MCQ (Single Correct Answer)
+1
-0

Identify the correct statement regarding corrosion of iron rod left exposed to atmosphere.

A

The reaction occurring at the cathodic area is:

$$ \mathrm{O}_2(\mathrm{~g})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{l})+4 \mathrm{e} \rightarrow 4 \mathrm{OH}^{-} $$

B

The reaction occurring at the cathodic area is:

$$ \mathrm{O}_2(\mathrm{~g})+4 \mathrm{H}^{+}(\mathrm{aq})+4 \mathrm{e} \rightarrow 2 \mathrm{H}_2 \mathrm{O}(\mathrm{l}) ; \mathrm{E}^0=+1.23 \mathrm{~V} $$

C

Reaction occurring at anodic area is:

$$ 2 \mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{O}_2(\mathrm{~g})+4 \mathrm{H}^{+}+4 \mathrm{e} $$

D

The overall reaction occurring during the corrosion process is:

$$ 2 \mathrm{Fe}_{(\mathrm{S})}+3 / 2 \mathrm{O}_2(\mathrm{~g})+6 \mathrm{H}^{+} \rightarrow 2 \mathrm{Fe}^{3+}+3 \mathrm{H}_2 \mathrm{O} ; \mathrm{E}^0=-1.23 \mathrm{~V} $$

2
COMEDK 2024 Evening Shift
MCQ (Single Correct Answer)
+1
-0

Given below are 2 statements: Assertion and Reason. Choose the correct option.

Assertion: When Molar conductivity for a strong electrolyte is plotted versus $$\sqrt{C}(\mathrm{~mol} / \mathrm{L})^{1 / 2}$$, a straight line is obtained with intercept equal to Molar conductivity at infinite dilution for the electrolyte and Slope equal to $$-\mathrm{A}$$. All electrolytes of a given type have the same $$\mathrm{A}$$ value.

Reason: At infinite dilution, strong electrolytes of the same type will have different number of ions due to incomplete dissociation.

A
Assertion is correct but Reason is incorrect statement.
B
Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
C
Both Assertion and Reason are incorrect statements.
D
Assertion is incorrect but Reason is correct statement.
3
COMEDK 2024 Evening Shift
MCQ (Single Correct Answer)
+1
-0

What is the quantity of charge, in Faraday units, required for the reduction of 3.5 moles of $$\mathrm{Cr}_2 \mathrm{O} 7^{2-}$$ in acid medium?

A
6.0
B
10.5
C
21.0
D
3.0
4
COMEDK 2024 Evening Shift
MCQ (Single Correct Answer)
+1
-0

A dry cell consists of a moist paste of $$\mathrm{NH}_4 \mathrm{Cl}$$ and $$\mathrm{ZnCl}_2$$ contained in a $$\mathrm{Zn}$$ casing which encloses a Carbon rod surrounded by black $$\mathrm{MnO}_2$$ paste. What is the role of $$\mathrm{ZnCl}_2$$ in it?

A
It prevents pressure being developed in the cell due to $$\mathrm{NH}_3$$ gas formation.
B
It serves as cathode thus permitting Carbon rod to act as anode.
C
It acts as the anode while Carbon rod acts as the cathode.
D
It keeps the contents dry and prevents leakage of electrolyte.
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