a) 42.66%
b) 47.64%
c) 25.95%
d) 30.21%

Answer: b
Explanation: Consider a unit cube of soil having spherical particles of diameter d.
Volume of each spherical particle = (π/6)d³
Total volume of container = 1*1*1=1
No. of solids in the container = (1/d)*(1/d)*(1/d)=(1/d³)
Volume of the solids V_s = (π/6)*d³*(1/d³)=(π/6)
Volume of the voids V_v = 1-(π/6)
Voids ratio e = (1-(π/6))/(π/6)
Porosity n = e/(1+e) = 0.9099/(+0.9099) = 0.4764
In percentage, n = 47.64%.