1
COMEDK 2025 Evening Shift
MCQ (Single Correct Answer)
+1
-0
Which of the following compounds has electrons symmetrically distributed in both $\mathrm{t}_{2 \mathrm{~g}}$ and $\mathrm{e}_{\mathrm{g}}$ orbitals?
A
$\left[\mathrm{CoF}_6\right]^{3-}$
B
$\left[M n(C N)_6\right]^{4-}$
C
$\left[\mathrm{Cr}\left(\mathrm{NH}_3\right)_6\right]^{3+}$
D
$\left[\mathrm{FeCl}_6\right]^{3-}$
2
COMEDK 2025 Evening Shift
MCQ (Single Correct Answer)
+1
-0

Identify the two incorrect electrochemical reactions shown as taking place in the given cells at the respective electrodes.

Cell Electrode Reaction
Lead-Storage Cell Cathode $\mathrm{Pb}+2 \mathrm{SO}_4{ }^{2-}+4 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow \mathrm{PbSO}_4+2 \mathrm{H}_2 \mathrm{O}+\mathrm{SO}_2$
Leclanche Cell Cathode $\mathrm{MnO}_2+\mathrm{NH}_4^{+}+2 \mathrm{e}^{-} \rightarrow \mathrm{MnO}+\mathrm{OH}+\mathrm{NH}_3$
Mercury Cell Anode $\mathrm{Zn} / \mathrm{Hg}+2 \mathrm{OH}^{-} \rightarrow \mathrm{ZnO}(\mathrm{s})+\mathrm{H}_2 \mathrm{O}+2 \mathrm{e}^{-}$
Fuel Cell Cathode $\mathrm{O}_2(\mathrm{~g})+2 \mathrm{H}_2 \mathrm{O}+4 \mathrm{e}^{-} \rightarrow 4 \mathrm{OH}^{-}$

A
C & D
B
A & C
C
B & D
D
A & B
3
COMEDK 2025 Evening Shift
MCQ (Single Correct Answer)
+1
-0
Choose the correct statement.
A
The plot of $[A]$ versus time " $t$ " for a zero order reaction is a horizontal line parallel to the $x$-axis which represents " $t$ "
B
For a first order reaction the time taken for $3 / 4^{\text {th }}$ completion is 2 times the half-life period.
C
For a second order reaction the rate of reaction with respect to reactant becomes 27 times when its concentration is tripled.
D
Molecularity of a chemical reaction is always greater than order of the reaction.
4
COMEDK 2025 Evening Shift
MCQ (Single Correct Answer)
+1
-0

Consider the following reaction

$$\text { Propyne }+\mathrm{CH}_3 \mathrm{MgBr} \xrightarrow{\text { dry ether }} \mathbf{X}$$

Identify ' X ' from the following.

A
But-2-yne
B
Propane
C
Methane
D
But-2-ene
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