CALCULATIONS :-

Points A & B are chosen on the graph.

Value of 10³ / T :-
i) corresponding to point A on the graph is = 3.15
& ii) corresponding to point B on the graph is = 3.05

Value of log₁₀R :-
i) corresponding to point A on the graph is = 2.65
& ii) corresponding to point B on the graph is = 2.55

So, slope of the graph, m = (2.65 - 5.55) / (3.15 - 3.05)
= 0.1 / 0.1
= 1.0

As, Eg = slope x 0.396 eV
Eg = 1.0 x 0.396 eV
= 0.396 eV.