A. Direction: Read the questions carefully. Circle the letter of your choice. 1. What component does air have that is essential for living things to survive? A. ammonia C. Oxygen B. nitrogen 2. What makes our air polluted? D. carbon dioxide A. Cutting of trees in the forests. B. Use of electric appliances at home. C. Spraying the farms with pesticides to kill the pests. D. Burning of gasoline and diesel by vehicles and factories. 3. In what way air pollution affects the plants? A. Slow down the growth of the plants. B. Makes plant good for animals to eat. C. Source of organic fertilizer for the plants. D. Protects the plants from being eaten by the animals. 4. Which of the following is a pollutant in the air? A. Oxygen C. sulfur dioxide B. nitrogen D. carbon dioxide 5. Which of the following will NOT be the result of overcrowding? A. Diseases spread easily. B. Organisms grow very healthy. C. Resources will be in limited supply. D. There is equal sharing of resources.​