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

The initial pressure of the system before decomposition for a first order gas phase reaction $A_{(g)} \rightarrow B_{(g)}+C_{(g)}$ was $\mathrm{P}_{\mathrm{i}}$. After lapse of time ' t ', total pressure of the system increased by ' x ' units and became $\mathrm{P}_{\mathrm{t}}$. The rate constant ' k ' for the reaction is given as:

A

$k=\frac{2.303}{t} \log \frac{P_i}{P_i+x}$

B

$k=\frac{2.303}{t} \log \frac{P_i}{2 P_i-P_t}$

C

$k=\frac{2.303}{t} \log \frac{P_i}{2 P_i+P_t}$

D

$k=\frac{2.303}{t} \log \frac{P_i}{P_i-P_t}$

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

Which of the following is an INCORRECT match?

A

First lonization Enthalpies - $N aA l

B

Metallic character      - $A l>M g>B>K$

C

lonic size $\quad\quad-\quad \mathrm{Na}^{+}>\mathrm{Mg}^{+2}>\mathrm{Al}^{+3}>\mathrm{Si}^{+4}$

D

Electron Gain enthalpy $\quad-\mathrm{F}<\mathrm{Cl}>\mathrm{Br}>\mathrm{I}$

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

Two statements $[A]$ and $[B]$ are given below. Choose the correct option.

A) Protonated $\mathrm{R}-\mathrm{C} \mathrm{H}_2-\mathrm{OH}$ can serve as Electrophiles while neutral $\mathrm{R}-\mathrm{OH}$ acts as a Nucleophile.

B) The bond between $\mathrm{O}-\mathrm{H}$ cleaves when $\mathrm{R}-\mathrm{CH}_2-\mathrm{OH}$ acts as Electrophiles and the bond between $\mathrm{C}-\mathrm{O}$ cleaves when they act as Nucleophiles.

A

Both the statements $[A]$ and $[B]$ are correct

B

Both the statements $[A]$ and $[B]$ are wrong

C

Statement $[B]$ is correct but $[A]$ is wrong

D

Statement $[\mathrm{A}]$ is correct but $[\mathrm{B}]$ is wrong

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

The frequency of photon which is emitted during a transition of electron of $\mathrm{He}^{+}$ion from fifth energy level to third energy level will be:

A

$1.34 \times 10^{-14} \mathrm{~s}^{-1}$

B

$9.39 \times 10^{14} \mathrm{~s}^{-1}$

C

$2.34 \times 10^{14} \mathrm{~s}^{-1}$

D

$8.29 \times 10^{-14} \mathrm{~s}^{-1}$