1
JEE Main 2025 (Online) 29th January Morning Shift
MCQ (Single Correct Answer)
+4
-1

500 J of energy is transferred as heat to 0.5 mol of Argon gas at 298 K and 1.00 atm. The final temperature and the change in internal energy respectively are: Given: R = 8.3 J K-1 mol-1

A

368 K and 500 J

B

348 K and 300 J

C

378 K and 300 J

D

378 K and 500 J

2
JEE Main 2025 (Online) 29th January Morning Shift
MCQ (Single Correct Answer)
+4
-1

The molar conductivity of a weak electrolyte when plotted against the square root of its concentration, which of the following is expected to be observed?

A

Molar conductivity increases sharply with increase in concentration.

B

Molar conductivity decreases sharply with increase in concentration.

C

A small increase in molar conductivity is observed at infinite dilution.

D

A small decrease in molar conductivity is observed at infinite dilution.

3
JEE Main 2025 (Online) 29th January Morning Shift
MCQ (Single Correct Answer)
+4
-1

The correct option with order of melting points of the pairs (Mn, Fe), (Tc, Ru) and (Re, Os) is :

A

Fe < Mn, Ru < Tc and Re < Os

B

Fe < Mn, Ru < Tc and Os < Re

C

Mn < Fe, Tc < Ru and Re < Os

D

Mn < Fe, Tc < Ru and Os < Re

4
JEE Main 2025 (Online) 29th January Morning Shift
MCQ (Single Correct Answer)
+4
-1

The reaction $A_2 + B_2 \rightarrow 2AB$ follows the mechanism

$\begin{aligned} & A_2 \xlongequal[k_{-1}]{k_1} A+A \text { (fast) } \\\\ & A+B_2 \xrightarrow{k_2} A B+B \text { (slow) } \\\\ & A+B \rightarrow A B \text { (fast) }\end{aligned}$

The overall order of the reaction is :

A

3

B

2.5

C

1.5

D

2

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