Photochemical smog always contains

In case of which one of the following biogeochemical cycles, the weathering of rocks is the main source of release of nutrient to enter the cycle?

Biological Oxygen Demand (BOD) is a standard criteria for

Biological Oxygen Demand (BOD) is a standard criterion for -

For acid rain, the pH of rain water should be less than

Which one among the folowing is a non-conventional source of energy?