Question

In a science lab, Thomas used "universal indicator" to investigate the pH of some household products. He created a reference table that shows the color of universal indicator at different pH values. He also tests solutions of these pH values to see if they react with metals and records his observations.

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Thomas tested an unknown substance and found that the universal indicator turns purple and it does not react with metal. Based on this information, which of the following best predicts if the unknown substance is acidic, basic, or neutral?

A.

The unknown substance is neutral because it had the same result to that of the household product with a pH of 7 when tested with a metal.

B.

The unknown substance cannot be classified because there is not enough information being provided.

C.

The unknown substance is a base because the results are similar to that of the household product that had a pH of 10.

D
.

The unknown substance is an acid because the universal indicator results are similar to that of the household product that had a pH of 10.

Answer 1

C.

Purple from a universal indicator indicates a basic (alkaline) pH (around pH 10), and the lack of reaction with metal is consistent with a base (metals typically react with acids). Options A and D are inconsistent with the color, and B is wrong because the provided information is sufficient.