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प्रश्न
A beaker of concentrated hydrochloric acid has a pH of 1. What colour will full range universal indicator turn if it is added to this beaker? Is it a strong or a weak acid?
उत्तर
HCl, with a pH of 1, imparts a red colour when treated with a universal indicator. As the pH value decreases from 7, the acidity increases, as there is an increase in the concentration of hydrogen ions (H+). So, the given acid is very strong.
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संबंधित प्रश्न
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Lemon juice, Vinegar, Banking soda solution
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A solution turns phenolphthalein indicator pink. The most likely pH of this solution will be:
(a) 6
(b) 4
(c) 9
(d) 7
Fresh milk has a pH of 6. When milk changes into curd, the pH value will:
(a) become 7
(b) become less than 6
(c) become more than 7
(d) remain unchanged
The pH values of five solutions A, B, C, D and E are given below:
| A | 1 |
| B | 5 |
| C | 7 |
| D | 11 |
| E | 13 |
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).
Which of the following is not a natural indicator?
Assertion: Methyl orange and phenolphthalein are natural indicators.
Reason: Methyl orange is yellow in colour while phenolphthalein is pink.
