When hydrochloric acid is applied to a mineral and it effervesces (bubbles), which mineral is most likely present?

• A. Calcite (CaCO_3)
• B. Quartz (SiO_2)
• C. Halite (NaCl)
• D. Gypsum (CaSO_4 · 2H_2O)

Answer: (A)

Verified step by step guidance

1. Understand that effervescence (bubbling) when hydrochloric acid (HCl) is applied indicates a chemical reaction producing a gas, typically carbon dioxide (CO_2).
2. Recall that minerals containing carbonate ions (CO_3^{2-}) react with acids to produce CO_2 gas, causing effervescence.
3. Identify which mineral among the options contains carbonate ions: Calcite (CaCO_3) contains carbonate, while Quartz (SiO_2), Halite (NaCl), and Gypsum (CaSO_4 \cdot 2H_2O) do not.
4. Write the reaction for calcite with hydrochloric acid: \(\mathrm{CaCO_3 (s) + 2HCl (aq) \rightarrow CaCl_2 (aq) + CO_2 (g) + H_2O (l)}\); the CO_2 gas causes the bubbling.
5. Conclude that the mineral most likely present when effervescence occurs upon adding HCl is Calcite (CaCO_3).