Indicators and Neutralization MCQs
Indicators and Neutralization – MCQs with Answers & Explanations
Class: 7 | Subject: Science | Section: Acids, Bases and Salts | Topic: Indicators and Neutralization
Based Strictly on NCERT Syllabus | CBSE Board Examination Pattern
Based Strictly on NCERT Syllabus | CBSE Board Examination Pattern
1. Substances that change colour in acidic or basic solutions are called:
Answer: B. Indicators
Indicators are special substances that show whether a solution is acidic or basic by changing colour. Example: Litmus, turmeric.
Indicators are special substances that show whether a solution is acidic or basic by changing colour. Example: Litmus, turmeric.
2. Blue litmus paper turns red in:
Answer: B. Acids
Acids change blue litmus to red due to the presence of hydrogen ions.
Acids change blue litmus to red due to the presence of hydrogen ions.
3. Turmeric indicator turns red in:
Answer: B. Basic solution
Turmeric remains yellow in acids but turns reddish‑brown in bases like soap solution.
Turmeric remains yellow in acids but turns reddish‑brown in bases like soap solution.
4. China rose indicator gives dark pink colour with:
Answer: B. Acids
China rose turns acidic solutions dark pink and basic solutions green.
China rose turns acidic solutions dark pink and basic solutions green.
5. Neutralization is the reaction between:
Answer: B. Acid and base
In neutralization, acid reacts with base to form salt and water.
In neutralization, acid reacts with base to form salt and water.
6. Products of neutralization are:
Answer: A. Salt and water
Example: HCl + NaOH → NaCl + H₂O.
Example: HCl + NaOH → NaCl + H₂O.
7. Which is a natural indicator?
Answer: C. Litmus
Litmus is obtained from lichens and is a natural indicator.
Litmus is obtained from lichens and is a natural indicator.
8. Antacids give relief from acidity because they are:
Answer: B. Bases
Antacids neutralize excess stomach acid.
Antacids neutralize excess stomach acid.
9. Soil treatment uses neutralization to correct:
Answer: B. Soil acidity
Farmers add lime to neutralize acidic soil.
Farmers add lime to neutralize acidic soil.
10. Factory wastes are neutralized before disposal to:
Answer: B. Protect environment
Neutralization prevents damage to water bodies and soil.
Neutralization prevents damage to water bodies and soil.
11. Red litmus turns blue in bases because bases are:
Answer: B. Bases are bitter and change red litmus blue.
12. Which solution is neutral?
Answer: C. Distilled water is neutral (pH 7).
13. Phenolphthalein turns pink in:
Answer: B. It is colourless in acids, pink in bases.
14. Bee sting is treated with:
Answer: B. Baking soda neutralizes acidic bee venom.
15. Wasps stings are neutralized using:
Answer: A. Wasp venom is basic; vinegar (acid) neutralizes it.
16. Neutralization reaction is generally:
Answer: B. Heat is produced during neutralization.
17. Which is an artificial indicator?
Answer: D. Methyl orange is synthetic.
18. Tooth decay is prevented by using basic:
Answer: B. Toothpaste neutralizes mouth acids.
19. Neutral solution has pH:
Answer: C. pH 7 indicates neutrality.
20. Acid rain is neutralized by adding:
Answer: A. Bases neutralize acidic effect of acid rain.