Correct Answer - Option 1 : Zero
Concept:
Group index of a soil is given by
G.I = 0.2 a + 0.005 ac + 0.01 bd
a = It is the portion of % passing through 75 μ sieve greater than 35 but not exceeding 75 expressed as whole number in between [0-40].
b = It is the portion of % passing through 75 μ sieve greater than 15 but not exceeding 55 expressed as whole number in between [0-40].
c = It is the portion of the numerical liquid limit greater than 40 but not exceeding 60 expressed as whole number in between [0-20].
d = It is the portion of the numerical plasticity index greater than to 10 but not exceeding 30 expressed as whole number in between [0-20].
Calculation:
IP = 10%, Liquid Limit = 40%
% Passing through 75 micron is 35%
a = 35 - 35 = 0 < 40
a = 0
b = 35 - 15 = 20
c = WL - 40
c = 40 - 40 = 0
d = IP - 10
d = 10 - 10 = 0
G.I = 0.2 a + 0.005 ac + 0.01 bd
G.I = 0.2 × 0 + 0.005 × 0 × 0 + 0.01 × 20 × 0
G.I = 0