Correct Answer - Option 1 : 0.5
Explanation
The activity of the soil is defined as the ratio of plasticity index of the soil to the percentage of particles finer than 2μ or 0.002 mm.
\({A_t} = \frac{{{I_P}}}{c}\)
Ip = Plasticity index of the soil = LL - PL
LL = Liquid limit of the soil
PL = Plastic limit of the soil
Given,
LL = 40 %, PL = 30%
percentage of particles finer than 2μ or 0.002 mm (C) = 20%
Plasticity Index = = 40 – 30 = 10%
∴ Activity = 10/20 = 0.5