Question

A scientist mixes an unknown powder into a beaker of water. He then uses an indicator and finds that the pH of the resulting solution is 8.5. What can he infer from this observation?

The unknown powder was acidic.
The unknown powder decreased the hydrogen ion concentration of the water.
The indicator used can measure only basic solutions.
The powder contains hydrogen ions.

Answer 1

A ph higher than 7 is basic so you can eliminate a.  The indicator can be used to measure both acids and bases so you can eliminate c.   Hydrogen ions are from acids, so the answer is that the powder decreased the hydrogen ions in the water.

Answer 2

Answer: Option (b) is the correct answer.

Step-by-step explanation:

When we measure the pH of a solution then we get to know whether the given solution is acidic or basic in nature.

So, if pH of the solution is less than 7 then the solution is acidic in nature whereas when pH of the solution is more than 7 then the solution is basic in nature. And, when the pH of the solution is equals to 7 then the solution is neutral.

Hence, when pH of the given solution becomes 8.5 then it means the solution has become basic in nature as there occurs decrease in hydrogen ion concentration and increase in hydroxide ions concentration.

Thus, we can conclude that it can be inferred from the given information that the unknown powder decreased the hydrogen ion concentration of the water.