# The group index for a soil, whose liquid limit is 40 percent, plasticity index is 10 percent and percentage passing 75 micron IS Sieve is 35, is :

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The group index for a soil, whose liquid limit is 40 percent, plasticity index is 10 percent and percentage passing 75 micron IS Sieve is 35, is :
1. Zero
2. 3
3. 5
4. 7

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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