consider the following system at equilibrium. caco3(s) ⇌ ca2+(aq) + co32-(aq) the addition of which compound…

Explanation:

Step1: Understand common - ion effect

The common - ion effect occurs when an ion is added to a solution that already contains that ion, causing a shift in equilibrium according to Le - Chatelier's principle. In the given equilibrium $CaCO_3(s)\rightleftharpoons Ca^{2 + }(aq)+CO_3^{2 - }(aq)$, we need to find a compound that will introduce either $Ca^{2+}$ or $CO_3^{2 - }$ ions.

Step2: Analyze each option

• $CCl_4$: It is a non - ionic compound and will not introduce any of the relevant ions.
• $CO_2$: It will not directly introduce $Ca^{2+}$ or $CO_3^{2 - }$ ions into the solution.
• $CuSO_4$: It will introduce $Cu^{2+}$ and $SO_4^{2 - }$ ions, not $Ca^{2+}$ or $CO_3^{2 - }$ ions.
• $Na_2CO_3$: It dissociates in solution as $Na_2CO_3(s)\rightarrow 2Na^{+}(aq)+CO_3^{2 - }(aq)$. It will introduce $CO_3^{2 - }$ ions, which is a common ion in the given equilibrium.

Answer:

D. $Na_2CO_3$