(a) (i) A first order reaction is $20%$ complete in $10$ minutes. Calculate the time taken when $80%$ of the reaction will be completed. [Given : $\log 5 = 0\cdot7$, $\log 4 = 0\cdot6$] (ii) For a chemical reaction $\text{R} \rightarrow \text{P}$, variation in $\ln[\text{R}]$ vs. time (t) graph is given below : (I) Predict the order of the reaction. (II) Write the slope of the curve. OR (b) (i) For first order reaction, calculate the ratio between the time taken to complete $\frac{3}{4}^{\text{th}}$ of the reaction and the time taken to complete half of the reaction. (ii) (I) What is meant by a complex reaction ? (II) Give an example of a pseudo first order reaction.