According to the Arrhenius equation,in a graph of $\log k$ versus $\frac{1}{T}$,the slope will be . . . . . . .

$A$ catalyst:

The time required for $10 \%$ completion of a first order reaction at $298 \,K$ is equal to that required for its $25 \%$ completion at $308 \,K$. If the value of $A$ is $4 \times 10^{10} \,s^{-1}$,calculate $k$ at $318 \,K$ and $E_a$.

An increase in the concentration of the reactants of a reaction leads to a change in:

For a gaseous reaction,a large increase in the rate of reaction with a small increase in temperature indicates:

For a first order reaction $(A \rightarrow B)$,the temperature $(T)$ dependent rate constant $(k)$ in $s^{-1}$ was found to follow the equation: $\log k = \left(-\frac{20}{T}\right)+4$. The activation energy $(E_a)$ and pre-exponential factor $(A)$ respectively,are