The correct option is (a).
Explanation
Electrical conductivity in liquids is determined by the presence of free-moving charged particles, specifically ions. Liquids that contain dissolved acids, bases, or salts dissociate into cations and anions, allowing them to conduct electricity (electrolytes). Liquids lacking free ions act as insulators.Statement-wise Analysis:
- 1. Lemon Juice (Correct): Lemon juice contains citric acid. In an aqueous solution, the acid dissociates to release hydrogen ions ($H^+$) and citrate ions. These free ions facilitate the flow of electric current.
- 2. Vinegar (Correct): Vinegar is a solution of acetic acid in water. It dissociates into acetate ions and hydrogen ions. Although it is a weak acid, the presence of these ions makes it a conductor of electricity.
- 3. Distilled Water (Incorrect): Distilled water is chemically pure and free from dissolved salts and minerals. Due to the absence of free ions, it acts as an electrical insulator. (Tap water typically conducts electricity due to dissolved impurities).
- 4. Vegetable Oil (Incorrect): Vegetable oil consists of non-polar organic molecules (lipids). These molecules do not dissociate into ions, meaning there are no charge carriers available to conduct electricity.
Key Takeaway: Liquids conduct electricity only when they contain dissolved electrolytes (acids, bases, or salts) that provide free ions. Pure water and non-polar organic liquids do not conduct electricity.