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प्रश्न
A sample of rain water turned universal indicator paper yellow. What would you expect it pH to be? Is it a strong or a weak acid?
उत्तर
A universal indicator shows a greenish-yellow colour for pH 6 and orange yellow for pH 5. This means that if the indicator turns yellow, the pH should be between these two values. Hence, it must have a pH value between 5 and 6. As the pH is closer to 7 (between 5 and 6), it is a weak acid.
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संबंधित प्रश्न
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.
- 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?
Fill in the blank in the following sentences:
Acids have a ..........................taste and they turn..........................litmus to..........................
Fill in the following blank with suitable words:
Neutral substances have a pH of ................
Explain the pH change as the cause of tooth decay. How can tooth decay caused by pH change be prevented?
Separate the following into substances having pH values above and below 7. How do these influence litmus paper?
(i) Lemon juice
(ii) Solution of washing soda
(iii) Toothpaste
(iv) Vinegar
(v) Stomach juices
Someone put some universal indicator paper into vinegar. The pH is 3. What does this tell you about the vinegar?
Name the acid present in vinegar.
Write a note on:
Methyl orange
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?
