How does an acid–base indicator react when placed in an acidic solution?

it changes color.
it dissolves.
it increases the ph of the solution.
it releases hydroxide ions.

Option (a) is the correct answer.

Explanation:

An acid-base indicator is an indicator which changes color according to the pH of solution in which it is placed.

For example, phenolphthalein is an acid-base indicator.

Thus, we can conclude that out of the given options, an acid–base indicator react by changing color when placed in an acidic solution, is the correct option.

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.