Answer the following :

Question

Accepted Answer

## Model Answer **(i)** The tomato juice with pH 4.6 will taste **sour**. Since its pH is less than 7, it is acidic in nature, and acids taste sour. **(ii)** A **strong acid** completely dissociates (ionises) in aqueous solution to produce a large number of H⁺ ions. A **weak base** partially dissociates in aqueous solution, producing a small number of OH⁻ ions. **(iii)** Acid rain lowers the pH of river/lake water. Aquatic animals are adapted to survive within a specific pH range. When pH falls below this range due to acid rain, their survival becomes difficult and they may die. --- ## Explanation - **(i)** Any pH < 7 = acidic = sour taste. Direct and simple — state it clearly. - **(ii)** Key contrast: "complete ionisation" (strong acid) vs "partial ionisation" (weak base). Mention the ions produced (H⁺ and OH⁻ respectively). - **(iii)** The logic chain is: acid rain → lower pH of water → outside tolerable range for aquatic life → difficult survival. Follow this chain for full marks.

Science — CBSE Class 10 board question