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

Two statements, Assertion and Reason are given below. Choose the correct option.

Assertion: n-propyl tert-butyl ether can be readily prepared in the laboratory by Williamson's synthesis.

Reason: The reaction occurs by $$\mathrm{S}_{\mathrm{N}} 1$$ attack of Primary alkoxide on Tert-alkyl halide to give good yield of the product, n-propyl tert-butyl ether.

A
Assertion is incorrect bur reason is correct.
B
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
C
Assertion is correct but Reason is incorrect.
D
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
3
COMEDK 2024 Evening Shift
MCQ (Single Correct Answer)
+1
-0

Two statements, Assertion and Reason are given. Choose the correct option from the following.

Assertion: In the secondary structure of RNA, double helix structure is formed.

Reason: In the double structure of RNA, two nucleic acid chains are wound about each other and held together by hydrogen bonds between pairs of bases

A
Assertion is correct but Reason is incorrect.
B
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
C
Assertion is incorrect but Reason is correct.
D
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
4
COMEDK 2024 Evening Shift
MCQ (Single Correct Answer)
+1
-0

An inorganic compound $$\mathrm{W}$$ undergoes the following reactions:

$$ \begin{gathered} W+\frac{\mathrm{Na}_2 \mathrm{CO}_3}{\mathrm{O}_2 / \text { heat }} \rightarrow X+\frac{\mathrm{H}^{+}}{} \rightarrow Y_{(s)} \\ Y(a q)+\mathrm{KCl}(\mathrm{aq}) \rightarrow Z_{(S)} \end{gathered} $$

Z appears in the form of orange crystals and is used as an oxidising agent in acid medium. Identify the compound W.

A
$$\mathrm{K}_2 \mathrm{CrO}_4$$
B
$$\mathrm{FeCr}_2 \mathrm{O}_4$$
C
$$\mathrm{Cu}(\mathrm{CrO}_2)_2$$
D
$$\mathrm{Na}_2 \mathrm{CrO}_4$$
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