Plankton are micro organisms that live in water bodies such as seas and ponds. They feed on other aquatic micro organisms that make food using sunlight. An oil spill has occurred on the sea near the south of Singapore.

Which one of the following graphs shows the population of plankton in the area affected by the oil spill?

Study the given statements.

I. Obtaining wood to make paper.

II. Poisoning of the soil by weed killers.

III. Making land available for growing crops.

IV. Digging for fuels and minerals from ground.

Which of the above activities are cause of deforestation?

Which of the following gases is not a green house gas?

Which of the following graph is correctly represented?

Which one of the following is not used for disinfection of drinking water?

Greenhouse effect is due to presence of