Observe the following set up :

(a) Which of the bulb glows ?
(b) Give reason for each of the case.
(c ) What would be the change observed if the content of the beaker B is replaced by NaOH solution ?

Explanation

(a) Bolb C
(b) Glucose and alcohol do not dissociate ions when dissolved in water as they are covalent compounds. As there is no movement of ions, bulb does not glow. HCl being an acid, releases `H^(+)` when dissolved in water thereby helps in conducting electricity. Hence the bulb glows.
(c ) If beaker B is replaced by NaOH solution, the bulb glows. This is because NaOH being a base, releases OH - ions to the solution which conducts electricity.