NEET Chemistry NEET PYQ-Chemical Kinetics

The rate constant for a first order reaction is\[4.606\times {{10}^{3}}{{s}^{1}}\]. The time required to reduce 2.0 g of the reactant to 0.2 g is: [NEET 2020]

A) 200 s

B) 500 s

C) 1000 s

D) 100 s

Correct Answer: B

Solution :

[b] \[K\frac{2.303}{t}\log \frac{{{A}_{0}}}{A}\] (First order rate equation)

\[4.606\times {{10}^{-3}}=\frac{2.303}{t}\log \frac{2}{0.2}\]

\[t=\frac{2.303}{4.606\times {{10}^{-3}}}\times \log \,10\]

\[=\frac{{{10}^{3}}}{2}=500\,\,\sec \]