Final answer:
Lemon juice is the substance that will give an aqueous solution with a pH less than 7, as it is acidic, whereas baking soda and ammonia are basic and distilled water is neutral. Option 1 is correct.
Step-by-step explanation:
The question is asking which substance will give an aqueous solution of pH less than 7. A substance with pH less than 7 is considered an acid. The given options are lemon juice, baking soda, ammonia, and distilled water. We can determine if these substances are acidic, basic, or neutral according to their pH levels.
Lemon juice has a pH less than 7 because it is acidic and tastes sour. Baking soda and ammonia are both basic with pH levels higher than 7; baking soda has a bitter taste, whereas ammonia is a common household cleaning product known for its basicity. Distilled water is neutral with a pH of exactly 7.
Based on this information, the substance that will give an aqueous solution of pH < 7 is lemon juice.
An aqueous solution that has a pH lower than 7 is considered acidic. From the given options, lemon juice would give an aqueous solution with a pH < 7. Lemon juice contains citric acid, which gives it an acidic taste and reduces its pH value.