EXPLANATION:Zero air void lineA curve representing the relationship between dry unit weight and water CONTENT of the compacted soil at zero % of air voids is called a zero air void line.Equation of zero air void line,\({γ _{d\max }} = \frac{{G{γ _w}}}{{1 + wG}}\)where,γdmax = Maximum dry unit weight of soilG = Specific gravityw = water content γw = unit weight of waterFrom the equation, it is clear that the unit weight of soil at zero voids depends on Specific gravity, water content, and unit weight of water.100 % saturation line: A curve representing the relationship between dry unit weight and water content of the compacted soil at 100 % the DEGREE of saturation is called the 100 % saturation line.Although 100 % saturation line CORRESPONDS to zero air void line x % saturation line in general does not corresponds to (100 - x) % air void line.