Question:
The water having more dissolved $\mathrm{O}_{2}$ is :
Correct Option: 4,
Solution:
On heating concentration of $\mathrm{O}_{2}$ in water decreases. So boiling water and water at $80^{\circ} \mathrm{C}$ having less $\mathrm{O}_{2}$ concentration. Polluted water also having less $\mathrm{O}_{2}$ concentration. So water at $4^{\circ} \mathrm{C}$ having maximum $\mathrm{O}_{2}$ concentration.