a) \(e=\frac{wG}{S}\)
b) e = wGS
c) \(e=\frac{wS}{G}\)
d) \(e=\frac{GS}{w}\)

Answer: a
Explanation: The degree of saturation is given by
S=\(\frac{V_w}{V_V}=\frac{e_w}{e}\) where e_w = water void ratio=eS ——-(1)
Water content w=\(\frac{W_w}{W_d}\)
w = \(\frac{e_wγ_w}{γ_s*1}\)
But γ_s = Gγ_w
∴ w = \(\frac{e_wγ_w}{Gγ_w}= \frac{e_w}{G}\)
e_w = wG ———–(2)
from equation (1) and (2)
\(e=\frac{wG}{S}\).