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प्रश्न
What is an indicator?
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उत्तर
An acid-base indicator is a chemical substance that indicates the acidic or basic nature of a solution by a suitable colour change.
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संबंधित प्रश्न
You have two solutions, A and B. The pH of solution A is 6 and pH of solution B is 8. Which solution has more hydrogen ion concentration? Which of this is acidic and which one is basic?
Do basic solutions also have H+ (aq) ions? If yes, then why are these basic?
Five solutions, A, B, C, D and E, when tested with universal indicator, showed pH as 4, 1, 11, 7 and 9, respectively. Which solution is
- neutral?
- strongly alkaline?
- strongly acidic?
- weakly acidic?
- weakly alkaline?
Arrange the pH in increasing order of hydrogen-ion concentration.
What colour does the following indicator turn when added to a base or alkali (such as sodium hydroxide)?
Litmus
Why should curd and other sour foodstuffs (like lemon juice, etc.) not be kept in metal containers (such as copper and brass vessels)?
A farmer has found that the pH of soil in his fields is 4.2. Name any two chemical materials which he can mix with the soil to adjust its pH.
State whether a solution is acidic, alkaline or neutral if its pH is:
(i) 9
(ii) 4
(iii) 7
(iv) 1
(v) 10
(vi) 3
Here are some results of solutions tested with universal indicator paper:
| Sulphuric acid | : Red |
| Metal polish | : Dark blue |
| Washing-up liquid | : Yellow |
| Milk of magnesia | : Light blue |
| Oven cleaner | : Purple |
| Car batter acid | : Pink |
Arrange the solutions in order of their increasing pH value (starting with the one with the lowest pH).
Name any two synthetic acid-base indicators.
A milkman adds a very small amount of baking soda to fresh milk. Why does this milk take a long time to set as curd?
