The correct option is A-3, B-1, C-2, D-4
Explanation
Acids are substances that taste sour and turn blue litmus red. Many acids occur naturally in plants and animals; these are known as organic acids. Identifying the specific acid present in common natural substances is a fundamental aspect of understanding acid-base chemistry.
Detailed Analysis:
- A. Lactic acid matches 3 (Curd): Lactic acid is formed in milk products like curd and sour milk due to the fermentation of lactose by bacteria such as Lactobacillus.
- B. Oxalic acid matches 1 (Spinach): Oxalic acid is a dicarboxylic acid found in significant quantities in leafy vegetables like spinach, as well as in tomatoes.
- C. Citric acid matches 2 (Citrus fruits): Citric acid is the primary acid found in citrus fruits such as lemons, oranges, and grapefruits, responsible for their sour taste.
- D. Formic acid matches 4 (Ant's sting): Formic acid (chemically known as Methanoic acid) is present in the sting of ants and bees. When an ant bites, it injects this acid into the skin, causing a burning sensation.
Key Takeaway:
Common natural sources of organic acids include Curd (Lactic acid), Spinach (Oxalic acid), Citrus fruits (Citric acid), and Ant stings (Formic/Methanoic acid).