Which of the following has pH value 7?
- AOption (a)
Pure water
- BOption (b)
Neutral solution
- COption (c)
Basic solution
- DOption (d)
Acidic solution
- EOption (e)
None of the above/More than one of the above
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Correct answer
None of the above/More than one of the above
Why this answer is correct
The correct answer is More than one of the above.
- Pure water - pH 7
- Neutral solution - pH 7
- Basic Solution - pH more than 7
- Acidic Solution - pH less than 7
Important Points
- Acidity and alkalinity are measured with a logarithmic scale called pH.
- pH is the negative logarithm of the hydrogen ion concentration: pH = −log [H+]
- The square brackets around the H+ mean "concentration" relative to pure water.
- A pH less than 7 is acidic and a pH greater than 7 is basic.
- An acid is a substance that donates hydrogen ions.
- An acid is dissolved in water, the balance between hydrogen ions and hydroxide ions is shifted.
- There are more hydrogen ions than hydroxide ions in the solution which makes the solution is acidic.
- A base is a substance that accepts hydrogen ions.
- A base is dissolved in water, the balance between hydrogen ions and hydroxide ions shifts the opposite way.
- Because the base "soaks up" hydrogen ions, the result is a solution with more hydroxide ions than hydrogen ions and makes the solution alkaline.
Key Points
| pH VALUE | H+ CONCENTRATION | EXAMPLES |
|---|---|---|
| 0 | 10000000 | battery acid |
| 1 | 1000000 | gastric acid |
| 2 | 100000 | lemon juice, vinegar |
| 3 | 10000 | orange juice, soda |
| 4 | 1000 | tomato juice, acid rain |
| 5 | 100 | black coffee, bananas |
| 6 | 10 | urine, milk |
| 7 | 1 | pure water, neutral solution |
| 8 | 0.1 | seawater, eggs |
| 9 | 0.01 | baking soda |
| 10 | 0.001 | milk of magnesia |
| 11 | 0.0001 | ammonia solution |
| 12 | 0.00001 | soapy water |
| 13 | 0.000001 | bleach, oven cleaner |
| 14 | 0.0000001 | liquid drain cleaner |