A) State and explain the observation made in boiling tube A. b) Write an equation for the reaction occurring in boiling tube A.

a) State and explain the observation made in:

(i) Boiling tube A
Observation: The black solid turns pinkish-brown.
Explanation: Copper (II) oxide (black) is reduced by carbon (charcoal) to form copper metal (pinkish-brown) and carbon dioxide gas.

(ii) Boiling tube B
Observation: The colorless solution turns milky/cloudy (or a white precipitate forms).
Explanation: The carbon dioxide gas produced in boiling tube A reacts with calcium hydroxide solution (limewater) to form insoluble calcium carbonate, which appears as a white precipitate.

b) Write an equation for the reaction occurring in:

(i) Boiling tube A

$$2CuO(s) + C(s) \xrightarrow{\text{heat}} 2Cu(s) + CO_2(g)$$

(ii) Boiling tube B

$$Ca(OH)_2(aq) + CO_2(g) \rightarrow CaCO_3(s) + H_2O(l)$$