Paper 1 · People, Development and Environment
Statement 1: Aquatic organisms depend on dissolved oxygen (DO) in water for respiration, which mainly depends on water temperature and the quantity of sediment. Statement 2: Biological Oxygen Demand (BOD) is the amount of oxygen consumed by bacteria while decomposing organic matter under aerobic conditions. Statement 3: Chemical Oxygen Demand (COD) is the amount of oxygen required for the chemical oxidation of total organic matter in water. Which of the above statements are true?
- Aquatic organisms depend on dissolved oxygen, which mainly depends on temperature and sediment
- BOD is the oxygen consumed by bacteria decomposing organic matter aerobically
- COD is the oxygen required for chemical oxidation of total organic matter in water
AOnly statements 1 and 2 are true
BOnly statements 2 and 3 are true
COnly statements 1 and 3 are true
DAll the statements 1, 2 and 3 are true ✓ Correct
Correct answer: (D) All the statements 1, 2 and 3 are true — All three statements are true, so that is the answer.
Explanation
★All three statements are true, so that is the answer.
★Dissolved oxygen supports aquatic life and depends on temperature and sediment.
★BOD is the oxygen bacteria use to break down organic matter aerobically.
★COD is the oxygen needed to chemically oxidize the organic matter in water.
★So each of the three statements is true.
★So the answer is that all the statements 1, 2 and 3 are true.
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