NCERT Class 7 Geography — Chapter 1: Air

With reference to the composition of the atmosphere, consider the following statements: 1. Nitrogen is the most plentiful gas in the air. 2. Carbon dioxide and argon together make up the bulk of the atmosphere. 3. Helium and hydrogen are present in the atmosphere in lesser quantities than nitrogen. Which of the statements given above is/are correct?

Which of the following gases is primarily responsible for the "greenhouse effect" by trapping the heat radiated from the earth?

Consider the following statements regarding the circulation of air: 1. When air is heated, it contracts and becomes heavier. 2. Cold air is denser and tends to sink down. 3. Air circulation occurs when cold air from surrounding areas rushes to fill the gap left by rising hot air. Which of the statements given above is/are correct?

With reference to the nitrogen cycle in the atmosphere, consider the following statements: 1. Plants absorb nitrogen directly from the air through their leaves. 2. Bacteria living in the soil and roots of some plants change the form of nitrogen for plant use. 3. Humans absorb all the nitrogen they inhale during breathing. Which of the statements given above is/are correct?

Which one of the following best explains why the balance of carbon dioxide in the atmosphere is getting disturbed?