Why should an unknown colourless solution not be identified only by looking at it?
Answer and explanation
Correct answer: Many acids and bases can be colourless, so indicators are needed.
Appearance alone is not a reliable chemical test. Many common acids, bases, and neutral solutions are colourless, so a person cannot determine their nature merely by looking at them. An appropriate indicator, pH paper, or universal indicator gives evidence through a controlled colour change; a pH meter can provide a numerical value. Options B and C make false universal claims, while D incorrectly says colour always gives an exact pH.
Frequently asked questions
What is the correct answer to this question?
Many acids and bases can be colourless, so indicators are needed.
Why is this the correct answer?
Appearance alone is not a reliable chemical test. Many common acids, bases, and neutral solutions are colourless, so a person cannot determine their nature merely by looking at them. An appropriate indicator, pH paper, or universal indicator gives evidence through a controlled colour change; a pH meter can provide a numerical value. Options B and C make false universal claims, while D incorrectly says colour always gives an exact pH.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
