Question

Mixtures of several indicators are known as the ______ indicator.

Answer 1

Universal indicator:

• The common indicators can't give the strength of the acid and the base for that universal indicator is needed.
• Universal indicator is used to detect whether the given solution is an acid or a base and when it is dipped in any of the solutions it changes its colours and informs us the type of solution and it is also a pH indicator and can be also used to detect the strength of the solution
• A universal indicator is a mixture of many indicators which give different colours at different pH values.
• When an acid or base solution is added to the universal indicator, it will produce a new colour which is used to find the pH value of the acid or the base solution by matching the colour with the colours on the pH colour chart.
• The most common universal indicator colours are:
  Red $0\le \mathrm{pH}\ge 3$, Yellow $3\le \mathrm{pH}\ge 6$, Green $\mathrm{pH}=7$, Blue $8\le \mathrm{pH}\ge 11$ and Purple $11\le \mathrm{pH}\ge 14$

Therefore, Mixtures of several indicators are known as the universal indicator.