Which of the following compounds will readily lose CO_2 when heated?

• A. NaHCO_3
• B. KNO_3
• C. NaCl
• D. CaCO_3

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the concept of thermal decomposition, which is the process where a compound breaks down into simpler substances when heated.
2. Step 2: Identify which compounds contain carbonate ions (CO_3^{2-}), as these are typically the ones that can lose CO_2 upon heating.
3. Step 3: Recognize that NaHCO_3 (sodium bicarbonate) and CaCO_3 (calcium carbonate) both contain carbonate or bicarbonate ions, making them candidates for releasing CO_2 when heated.
4. Step 4: Recall that KNO_3 (potassium nitrate) and NaCl (sodium chloride) do not contain carbonate ions and therefore do not release CO_2 upon heating; instead, they may decompose differently or remain stable.
5. Step 5: Conclude that compounds containing carbonate or bicarbonate ions, such as NaHCO_3 and CaCO_3, will readily lose CO_2 when heated due to their thermal decomposition reactions.