1
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

The Standard Reduction potential at $25^{\circ} \mathrm{C}$ for $\left(\mathrm{MnO}_4\right)^{-1} / \mathrm{H}^{+}$is +1.49 V . The $\mathrm{E}^0$ values for four Metal ions :

(a). $\mathrm{Co}^{3+} / \mathrm{Co}^{2+}$

(b). $\mathrm{Cr}^{3+} / \mathrm{Cr}$

(c). $\mathrm{Au}^{3+} / \mathrm{Au}$ and

(d). $\mathrm{Ag}^{+} / \mathrm{Ag}$

are $+1.81 \mathrm{~V},-0.74 \mathrm{~V},+1.50 \mathrm{~V}$ and +0.8 V respectively. Identify two of them which cannot be oxidised by $\left(\mathrm{MnO}_4\right)^{-1} / \mathrm{H}^{+}$

A
a & d
B
a & c
C
b & d
D
b & c
2
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
The best method for the separation of $o$-nitrophenol and $p$-nitrophenol from their mixture is :
A
Crystallisation
B
Steam distillation
C
Sublimation
D
Simple distillation
3
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
For the reaction $\mathrm{A}_2+\mathrm{B}_2 \cdots \cdots>2 \mathrm{AB}, \Delta \mathrm{H}_{\mathrm{f}}=-400 \mathrm{~kJ} / \mathrm{mol}$. The bond dissociation enthalpies of $\mathrm{A}_2$, $\mathrm{B}_2$ and AB are in the ratio $1: 0.75: 1$. What is the bond dissociation enthalpy of $\mathrm{B}_2$ in $\mathrm{kJ} / \mathrm{mol}$ ?
A
1600
B
2400
C
3200
D
800
4
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
The correct order of spin only magnetic moments among the following is: [Given: Atomic numbers: $\mathrm{Mn}=25, \mathrm{Fe}=26, \mathrm{Co}=27$ ]
A
$\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{4-}>\left[\mathrm{MnCl}_4\right]^{2-}>\left[\mathrm{CoCl}_4\right]^{2-}$
B
$\left[\mathrm{MnCl}_4\right]^{2-}>\left[\mathrm{CoCl}_4\right]^{2-}>\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{4-}$
C
$\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{4-}>\left[\mathrm{CoCl}_4\right]^{2-}>\left[\mathrm{MnCl}_4\right]^{2-}$
D
$\left[\mathrm{MnCl}_4\right]^{2-}>\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{4-}>\left[\mathrm{CoCl}_4\right]^{2-}$
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