Question

For a certain reaction \(R\rightarrow\) Product, the plot of concentration \([R]\) versus time has a negative slope as shown. The order of reaction is:

• A. \(1\)
• B. \(2\)
• C. \(2.5\)
• D. \(0\)

Hint:

For zero order reaction, \([R]\) versus time gives a straight line with slope \(-k\).

Answer 1

The Correct Option is D

Step 1: Recall integrated rate equation for zero order reaction.
For a zero order reaction: \[ [R]=[R]_0-kt \] This equation is similar to the straight-line equation: \[ y=c-mx \]

Step 2: Compare with graph.
If we plot: \[ [R]\text{ versus }t \] For zero order reaction, we get a straight line with negative slope. The slope is: \[ -k \]

Step 3: Identify order from the graph.
The graph given in the question shows a straight line decreasing with time. That means: \[ [R] \] decreases linearly with time. This is the characteristic graph of a zero order reaction.

Step 4: Final conclusion.
Therefore, the order of the reaction is: \[ 0. \]