Consider the following reactions
A → P₁ ; B → P₂ ; C → P₃ ; D → P₄,
The order of the above reactions are a, b, c, and d, respectively. The following graph is obtained when log[rate] vs. log[conc.] are plotted
Among the following, the correct sequence for the order of the reactions is :

Solution

Chemistry ma’am · 3 steps

On a log rate vs log concentration plot, the slope is the order, so rank the lines by steepness.

1. Take logs. For a reaction of order n, rate = k[X]ⁿ. Taking log on both sides turns this into a straight line.

   log(rate) = log k + n log[X]

2. Read the line. This is y = c + mx, so the slope of each line equals the order n. The intercept is only log k and says nothing about the order.

   Line	Steepness in the graph	Order
   D	steepest, rises almost vertically	d, the largest
   B	steep dashed line	b, second
   A	gentler dashed line	a, third
   C	flattest	c, the smallest

3. So. Ranking by slope gives d > b > a > c, which is option (a).

The idea to keep. Whenever you see log rate plotted against log concentration, the slope is the order. Compare steepness, and do not look at where the lines start.

Answer from the NTA final answer key. Solution by PrepWiser.