Chemistry - Chemical Kinetics Question with Solution | TestHub

At the intersection point ($t=30min$), $[A_4]=[A]⟹C_0-x=4x⟹x=0.2C_0$, which means 20% reaction is complete (A is correct). The rate constant is $k=\frac{2.303}{30}\log \left(\frac{C_0}{0.8C_0}\right)=\frac{2.303}{30}(\log 1.25)=\frac{2.303\times 0.1}{30}mi{n}^{-1}$. The half-life is $t_{1/2}=\frac{0.693}{k}=\frac{0.693\times 30}{2.303\times 0.1}=90min(\mathbf{B}\mathbf{is}\mathbf{correct})$. For first-order kinetics, the rate decreases exponentially over time, not linearly (C is incorrect). Since the fraction of reactant left at intersection ($0.8C_0$) is constant, the time is independent of $C_0$ (D is correct).