Consider the following statements:
- Both acids and bases change colour of all indicators.
- If an indicator gives a colour change with an acid, it does not give a change with a base.
- If an indicator changes colour with a base, it does not change colour with an acid.
- Change of colour in an acid and a base depends on the type of the indicator.
Which of these statements are correct?
(i) All four (ii) a and d (iii) b and c (iv) only d
Answer:
Let us go through all the statements:
1. Both acids and bases change colour of all indicators.
This is not true .
- There are several natural as well as man-made indicators that c hange colour when introduced to either acid or base , and are unable to distinguish from neutral solutions .
- For Example - Turneric , phenolphthalein
2. If an indicator gives a colour change with an acid, it does not give a change with a base.
- This is also not true.
- There are several indicators that change to different colours when introduced to acids and bases.
- For Example - Litmus Paper , China Rose , etc
3. If an indicator changes colour with a base, it does not change colour with an acid.
- This statement is also not true.
- Some indicators can change colours with both bases as well as acids .
- For Example - Litmus Paper , China Rose , etc
4. Change of colour in an acid and a base depends on the type of the indicator.
- The statement is true .
Hence, the correct answer is (d)
