Correct Answer - Option 2 : 0.34

__Concept:__

The relation between void ratio and porosity of soil sample is given as: \(n\; = \frac{e}{{1 + e}}\)

Where

n is porosity and e is void ratio.

__Calculation:__

Given: n = 0.25

\(n\; = \frac{e}{{1 + e}}\)

\(0.25 = \frac{e}{{1 + e}}\)

∴ e = 0.34

__Important Points:__

1. Porosity is the total volume of voids in a soil sample expressed in percentage of total volume of soil sample, while void ratio is the ratio of volume of voids to volume of solids in soil sample.

2. Porosity is always less than 100% but void ratio may be less than 1 or greater than or equal to 1.