A forms B ( $E_{1} = 70.0 kJ mo l^{- 1}$ ) and C ( $E_{2} = 50.0 kJ mo l^{- 1}$ ) by parallel first-order paths with equal pre-exponential factors. Select the correct statement(s).

A $k_{B} / k_{C}$ increases as $T$ increases.
BThe apparent activation energy of the disappearance of A lies between $50$ and $70 kJ mo l^{- 1}$ .
CAt sufficiently high $T$ , $k_{B} / k_{C}$ exceeds $1$ .
D $k_{B} / k_{C}$ is less than $1$ at every temperature.

Answer: A, B, D

With equal

A

k_{B} / k_{C} = exp [- (E_{1} - E_{2}) / RT]

: it is

3.29 \times 1 0^{- 4}

300

K and

0.090

1000

K, rising towards

1

but never exceeding it. The apparent activation energy is the

k

-weighted average

(k_{B} E_{1} + k_{C} E_{2}) / (k_{B} + k_{C})

, which must lie between

50

and

70