In the reaction, P + Q $$\to$$ R + S, the time taken for 75% reaction of P is twice the time taken for 50% reaction of P. The concentration of Q varies with reaction time as shown in the figure. The overall order of the reaction is

Bombardment of aluminium by $$\alpha$$-particle leads to its artificial disintegration in two ways : (i) and (ii) as shown. Products X, Y and Z, respectively, are

Plots showing the variation of the rate constant ($$k$$) with temperature ($$T$$) are given below. The point that follows Arrhenius equation is

For a first-order reaction A $$\to$$ P, the temperature (T) dependent rate constant (k) was found to follow the equation $$\log k = - (2000){1 \over T} + 6.0$$. The pre-exponential factor A and activation energy $$E_a$$, respectively, are