Q1: The coefficient of compressibility of soil, is the ratio of

ANS:B - strain to stress

Change in voids ratio is considered as strain. The strain is nothing but change in the dimension per unit original dimension. It is the ratio change in decrease void ratio to per unit Chang in increase pressure.

Soo, void ratio denoted volumetric strain.
And pressure as denoted stress.

It is the ratio of change in void ratio to change in stress. As void ratio changes the volume Will also change.

Hence it is the ratio of volumetric strain to stress. Coefficient of compressibility is the negative ratio of decrease in void ratio (i. E volumetric strain) to the increase in effective stress.

Increase in load will result in a decrease in void ratio and an increase in effective stress. The graph between void ratio and effective stress will be a parabolic curve with concavity upwards. The slope of this curve i.e. void ratio (y) /effective stress (x) will be negative. Hence the negative sign which will make the coefficient positive.