The eigen values of matrix $$\left[ {\matrix{ 9 & 5 \cr 5 & 8 \cr } } \right]$$ are

A water sample has a pH of 9.25. The concentration of hydroxyl ions in the water sample is

If a small concrete cube is submerged deep in still water in such a way that the pressure exerted on all faces of the cube is p, then the maximum shear stress developed inside the cube is

The ratio of actual evapo-transpiration to potential evapo-transpiration is in the range