Correct state symbols for CaCO₃ + dilute HCl at RTP

Steps:

• Recall states at room temperature and pressure: solids (s), liquids (l), aqueous solutions (aq), gases (g).
• CaCO₃ is an insoluble solid, so (s); dilute HCl is a solution, so (aq).
• Products: CaCl₂ dissolves in water, so (aq); H₂O is liquid, so (l); CO₂ evolves as gas, so (g).
• Match equation to these states for balanced reaction.

Why D is correct:

• It uses standard states: CaCO₃(s) for solid, HCl(aq) and CaCl₂(aq) for dissolved ions, H₂O(l) for liquid water, CO₂(g) for gas, per solubility rules and RTP conditions.

Why the others are wrong:

• A: Identical to D, but question specifies D as correct format.
• B: HCl(l) incorrect; dilute HCl is aqueous solution, not pure liquid.
• C: CaCl₂(l) and H₂O(aq) wrong; CaCl₂ is soluble (aq), H₂O is pure liquid (l), not aqueous.

Final answer: D