Test Yourself : Chapter 2 The atmosphere

Which of the following substances is/are element(s)?

(1) Mercury

(2) Dry ice

(3) Stainless steel

• A. (1) only
• B. (2) only
• C. (1) and (3) only
• D. (2) and (3) only

Which of the following substances is NOT a compound?

• A. Ice
• B. Sucrose
• C. Quartz
• D. Helium

Which of the following processes is/are a physical change(s)?

(1) Deposition of iodine vapour

(2) Burning of wood in air

(3) Diffusion of a dye in water

• A. (1) only
• B. (2) only
• C. (1) and (3) only
• D. (2) and (3) only

Which of the following statements concerning chemical changes are correct?

(1) Heating is always needed to start a chemical change.

(2) New substance(s) is/are always produced in a chemical change.

(3) Neutralization is a chemical change.

• A. (1) and (2) only
• B. (1) and (3) only
• C. (2) and (3) only
• D. (1), (2) and (3)

Which of the following statements concerning air is correct?

• A. Air is a compound of different gases.
• B. Different gases in air can be separated by fractional distillation.
• C. The percentage composition of oxygen (by volume) is higher than that of nitrogen.
• D. Hydrogen is one of the major components of air.

There are three main stages in separating the gases in air. Which of the following shows the stages in a correct sequence?

• A. purification → liquefaction → fractional distillation
• B. fractional distillation → purification → liquefaction
• C. liquefaction → purification → fractional distillation
• D. liquefaction → fractional distillation → purification

Which of the following statements concerning nitrogen is INCORRECT?

(Boiling points: nitrogen = −196°C, argon = −186°C, oxygen = −183°C)

• A. It is commonly used for food packaging.
• B. It is an odourless gas.
• C. It has the highest percentage composition in air (by volume).
• D. It is the lastly collected gas in the fractional distillation of liquid air.

Which of the following statements concerning fractional distillation of liquid air are correct?

(1) It is a chemical process.

(2) Carbon dioxide and water vapour are removed from the air at the early stage.

(3) Liquid oxygen and liquid argon are collected at the bottom of the fractionating column.

• A. (1) and (2) only
• B. (1) and (3) only
• C. (2) and (3) only
• D. (1), (2) and (3)