Due to a rise in temperature, the viscosity and the unit weight of the percolating fluid are reduced to 60% and 90% respectively. If other things remain constant, the coefficient of permeability A. increases by 25% B. increases by 50% C. increases by 33.3% D. decreases by 33.3%

The correct answer is A. increases by 25%.

The coefficient of permeability is a measure of how easily a fluid can flow through a porous medium. It is defined as the ratio of the volumetric flow rate of a fluid to the pressure gradient driving the flow.

The viscosity of a fluid is a measure of its resistance to flow. The unit weight of a fluid is its weight per unit volume.

When the viscosity and the unit weight of a fluid are reduced, the coefficient of permeability increases. This is because the fluid is able to flow more easily through the porous medium.

The following is a brief explanation of each option:

• Option A: increases by 25%. This is the correct answer. The coefficient of permeability increases by 25% when the viscosity and the unit weight of the fluid are reduced to 60% and 90% respectively.
• Option B: increases by 50%. This is incorrect. The coefficient of permeability increases by 25%, not 50%.
• Option C: increases by 33.3%. This is incorrect. The coefficient of permeability increases by 25%, not 33.3%.
• Option D: decreases by 33.3%. This is incorrect. The coefficient of permeability increases by 25%, not decreases by 33.3%.