Define the following terms:
(a).Standard solution
(b).Normal solution
(c).Indicator

Hint: A standard solution is a solution containing a clearly defined concentration of an element or a substance. A 1N solution contains 1 gram of solute equal weight per liter of solution. An indicator in chemistry refers to a pH indicator and is a chemical compound that is applied to a solution in small quantities to visually assess the pH of any solution.

Complete answer:
(a).Standard solution - A typical solution in analytical chemistry is a solution containing a clearly defined concentration of an element or a substance. To produce a given amount, a known weight of solute is dissolved. A standard substance, such as a primary standard, is used to prepare it. For the calculation of the quantities of other compounds, such as solutions for titration, regular solutions are used.
(b).Normal solution - Another way to measure solvent concentration is normality (N). It is similar to molarity, but in its expression of the solute quantity in a liter (L) of the solution, it uses the gram-equivalent weight of a liquid rather than the gram molecular weight expressed in molarity. A 1N solution contains 1 gram of solute equal weight per liter of solution. The expression of gram-equivalent weight involves an analysis of the valence of the solute. Valence represents an element's combining strength, often as determined by the number of hydrogen atoms that it can displace or combine with.
(c).Indicator – Indicator in chemistry refers to pH indicator. A pH indicator is a halochromic chemical compound that is applied to a solution in small quantities to visually assess the pH (acidity or basicity) of the solution. Normally, depending on the pH, the indicator allows the solution's color to change. Indicators may also display changes in some physical properties; olfactory indicators, for example, show changes in their odor.

Note:
All three solutions discussed in the solution above are frequently used in laboratory experiments called titrations. Titration is a delicate process and any slight impurity can ruin the whole experiment. Indicators (pH indicators) are special and they are usually chosen depending on the reagents and the conditions in which the experiment is to take place.