For a zero order reaction, the plot of concentration of reactant $v s$ time is (Hint: Consider the intercept on the concentration axis)

• A

  linear with +ve slope and non zero +ve intercept
• Correct answer
  B

  linear with -ve slope and non zero + ve intercept
• C

  linear with -ve slope and zero intercept
• D

  linear with +ve slope and zero intercept

Solution

Any reaction of zero order must obey the following equation $[A]=-k t+[A]_0 \text { or }[A]=[A]_0+k t$ This shows that, the concentration of reactant decreases linearly with time, as it is an equation of a straight line $(y=m x+c)$, the plot of $[A]$ versus $t$ will be straight line with slope $=-k$ and intercept on the concentration axis $=[A]_0$ as shown in figure.
Plot of $[A]$ versus $t$ for a reaction of zero order.

Hence, the correct answer is option: 'B'.