Indicators — Homi Bhabha Class 9 Chemistry MCQs with Solutions
Free Homi Bhabha Class 9 Chemistry Indicators MCQs with step-by-step solutions (10 questions). Part of Acids, Bases & Salts. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Indicators · medium · theory
An acid turns blue litmus paper:
A. green
B. blue
C. red ✓ Correct
D. colourless
Solution: Acids turn blue litmus red; bases turn red litmus blue.
Q2 — Indicators · medium · theory
A base turns red litmus paper:
A. yellow
B. blue ✓ Correct
C. red
D. colourless
Solution: Bases turn red litmus blue.
Q3 — Indicators · hard · theory
Phenolphthalein remains colourless in acidic solution but turns ______ in a basic solution:
A. red
B. pink ✓ Correct
C. yellow
D. blue
Solution: Phenolphthalein is colourless in acid and pink in base.
Q4 — Indicators · hard · theory
Methyl orange gives a ______ colour in an acidic solution:
A. yellow
B. green
C. red ✓ Correct
D. blue
Solution: Methyl orange is red in acid and yellow in base.
Q5 — Indicators · medium · theory
Which of the following is a natural indicator?
A. Turmeric ✓ Correct
B. Methyl orange
C. Universal indicator
D. Phenolphthalein
Solution: Turmeric (like red cabbage and china rose) is a natural indicator; the others are synthetic.
Q6 — Indicators · hard · theory
Substances like onion and vanilla, whose smell changes in acidic or basic media, are called:
A. olfactory indicators ✓ Correct
B. litmus
C. salts
D. universal indicators
Solution: Olfactory indicators show a change in odour to detect acids and bases.
Q7 — Indicators · easy · theory
A student dips a strip of blue litmus paper into an unknown solution and it turns red. The solution must be:
A. Acidic ✓ Correct
B. Neutral
C. A concentrated salt solution
D. Basic
Solution: Blue litmus turns red only in acidic solutions; bases keep it blue and neutral solutions cause no change.
Q8 — Indicators · easy · theory
A few drops of phenolphthalein are added to a colourless solution and it immediately turns pink. The solution is most likely:
A. Pure water
B. Sodium hydroxide solution ✓ Correct
C. Lemon juice
D. Dilute hydrochloric acid
Solution: Phenolphthalein stays colourless in acidic and neutral solutions and turns pink only in basic solutions such as sodium hydroxide.
Q9 — Indicators · medium · theory
A drop of curry (which contains turmeric) falls on a white shirt. When soap is scrubbed on the stain it turns reddish-brown, but on rinsing with water it becomes yellow again. This shows that the soap solution is:
A. A pure salt
B. Basic ✓ Correct
C. Neutral
D. Acidic
Solution: Turmeric is a natural indicator that turns reddish-brown in basic solutions. Soap solution is basic, so the stain changes colour; rinsing away the base restores the yellow.
Q10 — Indicators · hard · theory
Three solutions P, Q and R are tested with litmus. Red litmus turns blue only in P, blue litmus turns red only in Q, and neither litmus changes colour in R. The correct identification of P, Q and R is:
A. P acidic, Q basic, R neutral
B. P basic, Q acidic, R neutral ✓ Correct
C. P neutral, Q acidic, R basic
D. P basic, Q neutral, R acidic
Solution: Red litmus turning blue means P is basic; blue litmus turning red means Q is acidic; no change in either litmus means R is neutral.