(b)
Given, $k_{1}10^{10}e^{- 20,000/T}$
$k_{2} = 10^{12}e^{- 24,606/T}$
$k_{1} = k_{2}$
$10^{10}e^{- 20,000/T} = 10^{12}e^{- 24,606/T}$
$e^{\frac{- 20,000}{T} + \frac{24,606}{T}} = 10^{2}$
$e^{\frac{4,606}{T}} = 10^{2}$
On taking log both sides,
$\frac{4606}{2.303T} = \log 10^{2}$
$2\log{10 \times T = \frac{4606}{2.303}}$
$T = \frac{4606}{2.303 \times 2}$
$= \frac{4606}{4.606} = 1000\ K$