Answer:
The evolution of a colourless, odourless gas
Explanation:
If the pH = 1.5, Solution G is acidic.
Sodium carbonate is a base.
It will react with an acid to form carbonic acid, which decomposes into water and carbon dioxide.
2H⁺(aq) + CO₃²⁻(aq) ⟶ H₂CO₃(aq) ⟶ H₂O(l) + CO₂(g)
They observed the evolution of bubbles of a colourless, odourless gas.