Question

For the elementary reaction, \(M \to N\), the rate of disappearance of ‘M’ increases by a factor of 8 upon doubling the concentration of M. The order of the reaction with respect to M is}

• A. 1
• B. 2
• C. 3
• D. 4
• E. 5

Hint:

If doubling concentration multiplies rate by \(2^n\), then compare directly with the given factor to find order.

Answer 1

The Correct Option is C

Let the rate law be: \[ r=k[M]^n \] When concentration is doubled: \[ r'=k(2[M])^n = 2^n r \] Given rate increases by a factor of 8: \[ 2^n = 8 \] \[ 2^n = 2^3 \Rightarrow n=3 \]
Hence, the correct answer is: \[ \boxed{(C)\ 3} \]