Fill in the following blanks with suitable words :
The substances which show different colours in acidic, basic and neutral solutions are called ………

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a term that describes substances which change color in acidic, basic, and neutral solutions.

2. **Identifying Examples**: We can think of substances that are known to change color based on the pH of the solution. Common examples include litmus paper, phenolphthalein, and methyl orange.

3. **Defining the Term**: The substances that change color in response to the acidity or basicity of a solution are known as "indicators."

4. **Final Answer**: Therefore, the complete sentence is: "The substances which show different colours in acidic, basic and neutral solutions are called **indicators**."

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