Which of the following pairs is correct in terms of pH values?

(a) Tooth decay in humans: pH of mouth >5.5
(b) pH range of human body: 7.0 to 7.8
(c) Acid rain: pH of rain water >8

Correct option is A

The correct answer is (a) Only (b) is correct.

Explanation:

• Tooth decay in humans occurs when the pH of the mouth drops below 5.5. The acidic environment promotes the dissolution of enamel and causes tooth decay. A pH greater than 5.5 would not cause decay.
• The pH of the human body, specifically the blood, generally falls within a range of 7.35 to 7.45, which is slightly basic. However, the general pH range for the body is approximately 7.0 to 7.8.
• Acid rain typically has a pH less than 7 (usually between 4 and 5). It occurs due to the presence of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) in the atmosphere, which form sulfuric acid and nitric acid upon reacting with water vapor.

Information Booster:

Tooth Decay

• Cause: Bacteria in the mouth produce acids that break down tooth enamel.
• Process: Acidic byproducts from bacteria feed on sugars in food, leading to the formation of cavities.
• Effects: Pain, sensitivity, infection, and in severe cases, tooth loss.

Human Body pH

• Acid-Base Balance: The body maintains a delicate balance between acids and bases through the lungs and kidneys.
• Imbalance Effects:
• Acidosis: When blood pH falls below 7.35, leading to symptoms like fatigue and confusion.
• Alkalosis: When blood pH rises above 7.45, causing symptoms like muscle twitching and hand tremors.
• Regulation: The body regulates pH through buffers, breathing rate (CO2 regulation), and kidney function.