Question 1: Define oxygen evolution and explain its role in the development of Earth's atmosphere.

Answer: Oxygen evolution refers to the process of producing oxygen gas, primarily through photosynthesis in plants and algae, which contributed to the rise of oxygen levels in Earth's atmosphere over billions of years.

Question 2: Describe the chemical process by which plants produce oxygen during photosynthesis.

Answer: During photosynthesis, plants convert carbon dioxide and water into glucose and oxygen using sunlight energy, with the overall reaction: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.

Question 3: In an experiment, a plant is kept in water with a sodium bicarbonate solution. Explain why sodium bicarbonate is added.

Answer: Sodium bicarbonate provides carbon dioxide, which is necessary for photosynthesis, enabling the plant to produce oxygen in the experiment.

Question 4: Calculate the volume of oxygen produced in liters if 24 grams of water are split during electrolysis, given that 2 moles of water produce 1 mole of oxygen gas at standard temperature and pressure (STP). (Molar mass of water = 18 g/mol)

Answer: 2 liters

Question 5: Multiple Choice: Which of the following is NOT a component necessary for oxygen evolution in photosynthesis?

Answer: Oxygen gas

Question 6: Fill in the blank: The process by which oxygen is released into the atmosphere during photosynthesis involves the splitting of __________ molecules.

Answer: water

Question 7: Explain why oxygen evolution was a crucial factor in the development of aerobic life forms on Earth.

Answer: Oxygen evolution increased the oxygen levels in Earth's atmosphere, enabling the evolution of aerobic organisms that use oxygen for efficient energy production. This shift supported greater biological complexity and the development of ecosystems that rely on oxygen for respiration.

Question 8: Describe a simple practical experiment to demonstrate oxygen production from a leaf, including the variables involved and safety precautions.

Answer: An experiment can be conducted by placing a leaf in a test tube with water and exposing it to sunlight. Oxygen produced will cause bubbles to form on the leaf surface. Variables include light intensity (independent), amount of water (controlled), and temperature (controlled). Safety precautions involve handling hot equipment carefully and ensuring proper disposal of plant material.

Question 9: Data Analysis: A scientist measures the rate of oxygen production in a pond algae sample and finds it to be 0.5 liters per hour under certain light conditions. If the light intensity increases, what might you expect to happen to the rate of oxygen production? Explain your reasoning.

Answer: The rate of oxygen production is likely to increase because higher light intensity provides more energy for photosynthesis, leading to more oxygen being produced.