Nutrient enrichment of a lake will cause

What percentage of incoming solar radiation is reflected and absorbed by clouds and gases before reaching the Earth's surface (in $\%$)?

Which of the following pollutants are inevitably associated with the existence of man?

Which of the following is a degradable pollutant?

Which of the following statement$(s)$ is/are not correct regarding biomagnification?
$I.$ Heavy metals and persistent pesticides pass into the food chain and increase in amount per unit weight of organisms with the rise in trophic level due to their accumulation in fat.
$II.$ Accumulation of zinc can cause thinning of eggshells in birds.
$III.$ $DDT$ accumulation is a major cause of the killing of fish-eating birds.
$IV.$ Biomagnification occurs only in marine food chains.

Which of the following is an agrostologic method of soil conservation?