Question

What is order and molecularity of following reaction?

\[ \mathrm{NO}_{2(\mathrm{~g})}+\mathrm{NO}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{NO}_{(\mathrm{g})}+\mathrm{O}_{2(\mathrm{~g})} \]

• A. order 1 , molecularity 2
• B. order 2, molecularity 2
• C. order 2 , molecularity 3
• D. order zero, molecularity 2

Hint:

The reaction is written as an elementary step with two reacting molecules.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
Molecularity is the number of reacting species in an elementary step. Order is the sum of the powers in the rate law.

Step 2: Molecularity
Two \( \text{NO}_2 \) molecules collide, so the molecularity is 2.

Step 3: Order
For this elementary step the rate is \( r=k[\text{NO}_2]^2 \), so the order is 2.

Step 4: Compare the options
Order 2 and molecularity 2: option (B).

Final Answer:
The reaction has order 2 and molecularity 2. \[ \boxed{\text{(B) }\text{order 2, molecularity 2}} \]