1
COMEDK 2026 Morning Shift
MCQ (Single Correct Answer)
+1
-0

In the reaction,

$$ \mathrm{Cr}_2 \mathrm{O}_7^{2-}+4 \mathrm{H}_2 \mathrm{O}_2+2 \mathrm{H}^{+} \rightarrow 2 \mathrm{CrO}_5+\mathrm{H}_2 \mathrm{O} $$

The change in oxidation state of Cr is:

A

+6 to +3

B

+6 to +10

C

No change in oxidation state

D

+3 to +6

2
COMEDK 2026 Morning Shift
MCQ (Single Correct Answer)
+1
-0

$$ \text { Match the Coordination compounds in Column I with the type of stereoisomerism given in Column II exhibited by them. } $$

$$
\text { Column I }
$$
$$
\text { Column I }
$$
A $$
\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_2 \mathrm{Cl}_2\right]
$$
P fac-mer
B $$
\mathrm{Ni}\left[\left(\mathrm{NH}_3\right)_2 \mathrm{Cl}_2\right]
$$
Q cis -trans
C $$
\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3\left(\mathrm{NO}_2\right)_3\right]
$$
R only cis isomer shows optical isomerism
D $$
\left[\mathrm{Pt} \mathrm{Cl}_2(\mathrm{en})_2\right]^{2+}
$$
S does not exhibit isomerism.
A

$$ A-S \quad B-R \quad C-Q \quad D-P $$

B

$$ A-S \quad B-P \quad C-Q \quad D-R $$

C

$$ A-Q \quad B-S \quad C-O \quad D-R $$

D

$$ A-R \quad B-P \quad C-S \quad D-Q $$

3
COMEDK 2026 Morning Shift
MCQ (Single Correct Answer)
+1
-0

Identify the correct mathematical expression which represents the variation in molar conductivity of a weak acid having concentration C and ionisation constant $\mathrm{K}_{\mathrm{a}}$

( $\lambda_m^{\infty}=$ molar conductivity at infinite dilution, $\lambda_{\mathrm{m}}=$ molar conductivity at concentration C )

A

$K_a=\lambda_m^2 C / \lambda_m^{\infty}\left(\lambda_m^{\infty}-\lambda_m\right)$

B

$K_a=\lambda_m \lambda_m^{\infty}-\left(\lambda_m^{\infty}\right)^2+\lambda_m^2 C$

C

$\lambda_m+\lambda_m^{\infty}+K_a C^{\frac{1}{2}}=0$

D

$K_a=\lambda_m^2 C / \lambda_m^{\infty}\left(\lambda_m^{\infty}+\lambda_m\right)$

4
COMEDK 2026 Morning Shift
MCQ (Single Correct Answer)
+1
-0

Lassaigne's test for the detection of nitrogen fails in

A

$\mathrm{NH}_2-\mathrm{NH}_2 \mathrm{HCl}$

B

$\mathrm{NH}_2 \mathrm{CONHNH}_2 \mathrm{HCl}$

C

$\mathrm{C}_6 \mathrm{H}_5 \mathrm{NHNH}_2 \mathrm{HCl}$

D

$\mathrm{NH}_2 \mathrm{CONH}_2$