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**93) Select the correct relationship between the degree of saturation & air content from the following listed options.**

- a) ac = 1 ÷ S
- b) ac = 1 x S
- c) S = 1 + ac
- d) ac = 1 – S

Answer: d) ac = 1 – S

Explanation:

The ratio of the volume of air voids to the volume of voids in the air content.

ac = Va / Vv …(i)

The volume of water volume to the volume of voids in a given soil mass is called a degree of saturation.

S = Vw / Vv…(ii)

As we know that the volume of air & volume of water is combined, called a volume of void.

i.e. Vv = Vw + Va

∴ Va = Vv – Vw…(iii)

After substituting equation (iii) in equation (i), then we will get,

ac = Vv – Vw / Vv

ac = (Vv / Vv) – (Vw / Vv)

ac = 1 – (Vw / Vv)

ac = 1 – S…(from equation (ii))

∴ac = 1 – S is the correct relationship between the degree of saturation & air content in soil sample.