Question 1: Oxygen is a colourless, odourless gas that is essential for combustion and respiration. It makes up about 21% of the Earth's atmosphere. In the laboratory, oxygen can be identified using specific tests based on its reactivity and effect on other substances.

Answer: Oxygen is a colourless, odourless gas that supports combustion and respiration, making up 21% of the atmosphere.

Question 1: Describe how oxygen supports combustion differently compared to other gases such as nitrogen or carbon dioxide.

Answer: Oxygen supports combustion by reacting with the fuel and increasing the rate of burning, unlike nitrogen or carbon dioxide, which are inert and do not support combustion.

Question 2: Which of the following is a common laboratory test to confirm the presence of oxygen? A) Turns blue litmus paper red B) Relights a glowing splint C) Turns methyl orange red D) Produces a pungent smell

Answer: B

Question 3: Explain why a glowing splint is used to test for oxygen instead of a lit candle.

Answer: A glowing splint is used because it can relight in the presence of oxygen, indicating oxygen supports combustion. A lit candle would be extinguished due to lack of oxygen.

Question 4: Fill in the blank: When a glowing splint is inserted into a test tube containing oxygen, the splint will ____________, indicating the presence of oxygen.

Answer: relight

Question 1: Describe the safety precautions that should be taken when handling oxygen in a laboratory setting.

Answer: Ensure proper ventilation, avoid open flames or sparks, handle with appropriate regulators, and use safety goggles and gloves to prevent accidents or asphyxiation.

Question 2: List two common sources of industrial oxygen and mention one application for each.

Answer: One source is air separation units which produce oxygen for medical use; another is electrolysis of water used in welding and cutting metals.

Question 1: During a combustion experiment, a sample of a gas supports a glowing splint but does not support a flame. What gas could it be, and why does it behave this way?

Answer: It could be oxygen, which supports a glowing splint but not a flame if the flame was already extinguished or if the oxygen concentration is low; otherwise, oxygen generally supports both.

Question 2: Explain how oxygen’s role in respiration impacts human health and industry.

Answer: Oxygen is essential for cellular respiration, allowing humans to produce energy. In industry, oxygen is used in welding, medical treatments, and manufacturing processes. Lack of oxygen can lead to suffocation, while excess can cause oxidative stress or fires.