Temporary hardness of water is due to the presence of following salts of calcium and magnesium:
Now, the options aren't listed here, but based on common distractors in such questions, the incorrect options might include sulfates, chlorides, nitrates, or carbonates. Let's think. Permanent hardness is caused by sulfates and chlorides of calcium and magnesium, which don't precipitate on boiling. So if an option says sulfates, that's for permanent hardness. Carbonates might be tricky because calcium carbonate is part of the precipitate in temporary hardness, but the actual salts causing the hardness are the bicarbonates. So if an option lists carbonates, maybe that's incorrect because the temporary hardness comes from bicarbonates, which then form carbonates when heated.
Wait, the question is about which salts are present in temporary hardness. So the answer should be bicarbonates. Let me confirm: temporary hardness is due to dissolved bicarbonates of calcium and magnesium. When heated, these bicarbonates decompose into carbonates, water, and CO2. The carbonates precipitate out, removing the hardness. So the correct answer is calcium and magnesium bicarbonates. The distractors could be sulfates, chlorides, or carbonates. Carbonates might be a trick because they form the precipitate, but the original salts causing the hardness are the bicarbonates. So if an option lists carbonates, that's incorrect. Sulfates are part of permanent hardness. Chlorides as well. So if the options include bicarbonates as one of the choices, that's the right answer. The user's correct answer is missing the options, but based on standard questions, the correct answer is bicarbonates.
**Core Concept**
Temporary hardness of water is caused by dissolved **bicarbonates (HCO₃⁻)** of calcium and magnesium. Boiling decomposes these bicarbonates into insoluble carbonates, removing hardness. This contrasts with **permanent hardness**, caused by sulfates/chlorides, which resist boiling.
**Why the Correct Answer is Right**
Calcium and magnesium **bicarbonates** (Ca(HCO₃)₂ and Mg(HCO₃)₂) dissociate in water, releasing Ca²⁺ and Mg²⁺ ions that contribute to hardness. Upon boiling, these bicarbonates thermally decompose:
Ca(HCO₃)₂ → CaCO₃↓ + CO₂↑ + H₂O
Mg(HCO₃)₂ → MgCO₃↓ + CO₂↑ + H₂O
The precipitated carbonates remove hardness, distinguishing temporary from permanent types.
**Why Each Wrong Option is Incorrect**
**Option A:** Sulfates (e.g., CaSO₄) cause **permanent hardness**; they remain dissolved even after boiling.
**Option B:** Chlorides (e.g., MgCl₂) similarly contribute to permanent hardness, not temporary.
**Option C:** Carbonates (e.g., CaCO₃) are the **