If you are asking which is the most abundant, Uranium-238 is
<span>Cu⁺ is the only one of the ions in the list that will show 8 electrons in a d sublevel....its configuration will be Ar| 4s² 3d⁸
hope this helps</span>
Reactions can occur because of a precipitation reaction
<h3>Further explanation</h3>
Double-Replacement reactions, happens if there is an ion exchange between two ion compounds in the reactant to form two new ion compounds in the product
To predict whether this reaction can occur or not is one of them, the precipitation reaction. A precipitation reaction occurs if two ionic compounds which are dissolved reacted to produce one of the products of the ion compound does not dissolve. Formation of these precipitating compounds that cause reactions can occur
Chloride solution reacts with Sodium carbonate solution
CaCl₂(aq)+Na₂CO₃(aq)⇒CaCO₃(s)+NaCl(aq)
Because Calcium carbonate, CaCO₃ an insoluble solid , it will precipitates so that a reaction can occur
