Correct Option
The correct option is 1 only
Explanation
pH is a measure of the hydrogen ion concentration in a solution, determining its acidity or alkalinity. Biological systems and environmental phenomena operate within specific, often narrow, pH limits to maintain homeostasis and ecological balance.
Statement-wise Analysis
- Statement 1 is Correct: Living organisms are generally pH-sensitive and can survive only within a limited range of pH change. The human body functions physiologically within a narrow pH range of 7.0 to 7.8. Deviations outside this range can disrupt metabolic activities and enzymatic functions.
- Statement 2 is Incorrect: Pure water is neutral with a pH of 7.0. However, normal rainwater is naturally slightly acidic (pH approximately 5.6) due to the dissolution of atmospheric carbon dioxide, which forms carbonic acid. Rainwater is classified as acid rain only when its pH falls below 5.6, typically caused by the presence of pollutants like sulfur dioxide and nitrogen oxides.
Key Takeaway
Human physiological processes require a slightly alkaline environment (pH 7.0-7.8), whereas acid rain is defined by a pH value lower than 5.6, resulting from the dissolution of acidic pollutants in the atmosphere.