Final answer:
In a basic solution, hydroxide ions (OH-) are the most abundant. These ions accept protons from acids to produce water, indicating the solution's basic nature.
Step-by-step explanation:
The ions most abundant in a basic solution are hydroxide ions (OH-).
This is because bases can be ionic compounds like NaOH and Ca(OH)₂ which contain the hydroxide ion, OH-.
The hydroxide ion is known for accepting a proton from acids to form water (H+ + OH- → H₂O).
Therefore, in basic solutions, there is a higher concentration of OH- compared to H+.