Why is it easier to swim in sea water then in a river water?

Why is it easier to carry the same amount of water in two buckets, one in each hand rather than in a single bucket? (AS_(7))

When domestic sewage mixes with river water

Why soaps do not work in hard water ?

Why is water essential for life

Which of the following indicates the contamination of river water?

Why are ethers not soluble in water ?

Why is the pyramid of biomass in sea generally inverted?

Biochemical oxygen demand (BOD) in a river water