Final answer:
The solution with a hydronium ion concentration [H₃O+] of 6.0 × 10−3 M is acidic because this value is greater than the 1 × 10−7 M concentration that defines a neutral solution.
Step-by-step explanation:
Is a solution that has [H₃O+] = 6.0 × 10−3 M acidic, basic or neutral? To determine this, we can compare the given concentration of hydronium ions [H₃O+] to the standard concentration that defines neutral, acidic, and basic solutions. A neutral aqueous solution has [H₃O+] equal to 1 × 10−7 M, and if the concentration is higher than this, the solution is acidic, whereas if it is lower, the solution is basic.
In this case, the concentration of [H₃O+] is 6.0 × 10−3 M, which is greater than 1 × 10−7 M. Therefore, the solution is acidic. This is because a higher concentration of H₃O+ ions in a solution indicates a greater acidity. So the correct answer is option 1) Acidic.