1
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
What would be the cell potential for the Galvanic cell which is represented by the electrochemical reaction: $$ \begin{aligned} & 2 \mathrm{Cr}_{(\mathrm{S})}+3 \mathrm{Fe}^{2+}(0.02 \mathrm{M}) \rightarrow 2 \mathrm{Cr}^{3+}(0.2 \mathrm{M})+3 \mathrm{Fe} \\ & \mathrm{E}^0 \mathrm{Fe}^{2+} / \mathrm{Fe}=-0.42 \mathrm{~V} \quad \mathrm{E}^0 \mathrm{Cr}^{3+} / \mathrm{Cr}=-0.72 \mathrm{~V} \end{aligned} $$
A
0.3197 V
B
0.3364 V
C
0.2636 V
D
0.2803 V
2
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
The hydrogenation of Ethyne is carried out at 600 K . The same reaction when carried out in presence of a catalyst maintaining the same rate constant, the temperature required is only 400 K . If the catalyst lowers the Activation energy of the reaction by $20 \mathrm{~kJ} / \mathrm{mol}$, what is the value of $\mathrm{E}_{\mathrm{a}}$ ?
A
$60 \mathrm{~kJ} / \mathrm{mol}$
B
$100 \mathrm{~kJ} / \mathrm{mol}$
C
$50 \mathrm{~kJ} / \mathrm{mol}$
D
$80 \mathrm{~kJ} / \mathrm{mol}$
3
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

Complete the following 2 reactions A \& B by choosing appropriate reactants $[\mathrm{X}] \&[\mathrm{Y}]$.

COMEDK 2025 Afternoon Shift Chemistry - Alcohol, Phenols and Ethers Question 5 English

A
$[\mathrm{X}]=\mathrm{C}_6 \mathrm{H}_5 \mathrm{CHO}\qquad$ $[\mathrm{Y}]=\mathrm{CH}_3-\mathrm{CO}-\mathrm{CH}_3$
B
$[\mathrm{X}]=\mathrm{C}_6 \mathrm{H}_5 \mathrm{Br}\qquad$ $[\mathrm{Y}]=\mathrm{CH}_3 \mathrm{CH}_2-\mathrm{N}-\left(\mathrm{CH}_3\right)_2$
C
$[\mathrm{X}]=\mathrm{C}_6 \mathrm{H}_5 \mathrm{OH}\qquad$ $[\mathrm{Y}]=\mathrm{C}_6 \mathrm{H}_5-\mathrm{N}-\left(\mathrm{CH}_3\right)_2$
D
$[\mathrm{X}]=\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2\qquad$ $[\mathrm{Y}]=\mathrm{C}_6 \mathrm{H}_5 \mathrm{OH}$
4
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
The time needed for completion of $80 \%$ is $y$ times the half-life period of a first order reaction. What is the value of $y$ ?
A
0.648
B
3.46
C
2.32
D
0.322
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