In a certain  reaction the standard enthalpy change and the standard entropy change are 400kJ mol^-1 and 200JK^-respectively. At what temperature the reaction becomes non spontaneous ?

$$\begin{gathered} ∆{\mathrm{H}}_{\mathrm{r}} = 400\mathrm{kJ}/\mathrm{mole} ∆\mathrm{S} = 200{\mathrm{JK}}^{-1} \\ \mathrm{The} \mathrm{reaction} \mathrm{becomes} \mathrm{non} \mathrm{spontaneous} \mathrm{when} \\ ∆\mathrm{H} - \mathrm{T}∆\mathrm{S}>0 \mathrm{i}.\mathrm{e}., ∆\mathrm{H} > \mathrm{T}∆\mathrm{S} \\ \mathrm{When} \mathrm{T} = 2000 \mathrm{K} ∆\mathrm{H} = \mathrm{T}∆\mathrm{S} \\ \mathrm{When} \mathrm{T} > 2000 \mathrm{K} ∆\mathrm{H} < \mathrm{T}∆\mathrm{S} \\ \mathrm{When} \mathrm{T} < 2000 \mathrm{K} ∆\mathrm{H} > \mathrm{T}∆\mathrm{S} \\ \therefore \mathrm{T}=1990\mathrm{K} \end{gathered}$$