Q21 / 160 · TS EAMCET 2023 (14 May Shift 2) · Chemistry
For reaction $2 \mathrm{~A}+\mathrm{B} \longrightarrow \mathrm{D}+\mathrm{E}$, following mechanism has been proposed $\mathrm{A}+\mathrm{B} \longrightarrow \mathrm{C}+\mathrm{D}$ (Is slow) and $\mathrm{A}+\mathrm{C} \rightarrow \mathrm{E}$ (Is fast).
- A$\mathrm{r}=\mathrm{K}[\mathrm{A}]^2[\mathrm{~B}]$
- Correct answerB$\mathrm{r}=\mathrm{K}[\mathrm{A}][\mathrm{B}]$
- C$r=K[A]$
- D$\mathrm{r}=\mathrm{K}[\mathrm{A}][\mathrm{C}]$
Solution
$$
2 \mathrm{~A}+\mathrm{B} \rightarrow \mathrm{D}+\mathrm{E}
$$
Mechanism
$$
\begin{aligned}
& \mathrm{A}+\mathrm{B} \rightarrow \mathrm{C}+\mathrm{D} \ldots \ldots \ldots \ldots \text { slow } \\
& \mathrm{A}+\mathrm{C} \rightarrow \mathrm{E} \ldots \ldots \ldots \ldots \ldots \ldots \text { fast }
\end{aligned}
$$
R.D.S is always a slow step
$$
\mathrm{R}=\mathrm{K}[\mathrm{A}]^{\prime}[\mathrm{B}]^{\prime}
$$
Hence, the correct answer is option: 'B'.