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Acids, Bases & Salts — Homi Bhabha Exam Chemistry MCQs with Solutions
Free Homi Bhabha Exam Chemistry Acids, Bases & Salts MCQs with step-by-step solutions covering Indicators, pH Scale, Chemical Properties, Neutralization, Everyday Salts. Practise online on Prepizo — no login needed.
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Sample questions with solutions
Q1 — 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.
Q2 — 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.
Q3 — 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.
Q4 — pH Scale · hard · theory
Of two solutions, one has pH 2 and the other pH 5. The more acidic solution is the one with pH:
A. 5
B. neither is acidic
C. both are equal
D. 2 ✓ Correct
Solution: Lower pH means greater acidity, so pH 2 is more acidic than pH 5.
Q5 — pH Scale · hard · theory
A solution turns red litmus blue. Its pH is most likely:
A. exactly 0
B. greater than 7 ✓ Correct
C. less than 7
D. exactly 7
Solution: Turning red litmus blue indicates a base, which has pH greater than 7.
Q6 — Chemical Properties · hard · theory
The gas evolved when an acid reacts with a metal carbonate (e.g. limestone) is:
A. carbon dioxide ✓ Correct
B. oxygen
C. chlorine
D. hydrogen
Solution: Acid + carbonate → salt + water + carbon dioxide, which turns lime water milky.
Q7 — Chemical Properties · hard · theory
The gas produced when a metal reacts with an acid is tested by bringing a burning splint near it; a positive test gives:
A. a milky colour
B. a "pop" sound ✓ Correct
C. a red colour
D. a green flame
Solution: Hydrogen gas burns with a characteristic "pop" sound.
Q8 — Chemical Properties · hard · theory
Acids conduct electricity in aqueous solution because they:
A. are metals
B. produce no ions
C. produce ions (H⁺) in water ✓ Correct
D. contain oxygen only
Solution: Acids ionise in water to give mobile ions (including H⁺), which carry the current.
Q9 — Neutralization · hard · theory
Hydrochloric acid reacts with sodium hydroxide to give:
A. sodium and chlorine
B. sodium chloride and water ✓ Correct
C. sodium carbonate
D. hydrogen and oxygen
Solution: HCl + NaOH → NaCl + H₂O (a neutralisation).
Q10 — Neutralization · hard · theory
A bee sting, which is acidic, can be soothed by applying:
A. baking soda (a mild base) ✓ Correct
B. common salt
C. vinegar (an acid)
D. lemon juice (an acid)
Solution: A mild base like baking soda neutralises the acidic sting.
Q11 — Neutralization · hard · theory
Toothpastes are usually basic in nature so that they can:
A. dissolve the teeth
B. produce hydrogen gas
C. neutralise the acids formed by bacteria in the mouth ✓ Correct
D. increase mouth acidity
Solution: Basic toothpaste neutralises acids that would otherwise attack tooth enamel.
Q12 — Everyday Salts · hard · theory
Washing soda, used for cleaning, is chemically:
A. sodium carbonate (Na₂CO₃·10H₂O) ✓ Correct
B. sodium chloride
C. calcium hydroxide
D. sodium hydrogen carbonate
Solution: Washing soda is hydrated sodium carbonate, Na₂CO₃·10H₂O.
Q13 — Everyday Salts · hard · theory
Bleaching powder, used to disinfect water, is chemically:
A. sodium carbonate
B. sodium chloride
C. calcium oxychloride (CaOCl₂) ✓ Correct
D. calcium carbonate
Solution: Bleaching powder is calcium oxychloride, CaOCl₂.
Q14 — 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.
Q15 — Indicators · medium · theory
A base turns red litmus paper:
A. yellow
B. blue ✓ Correct
C. red
D. colourless
Solution: Bases turn red litmus blue.
Q16 — 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.
Q17 — pH Scale · medium · theory
The pH scale is used to measure the ______ of a solution and ranges from:
A. temperature; 0 to 100
B. acidity or basicity; 0 to 14 ✓ Correct
C. mass; 0 to 7
D. density; 1 to 10
Solution: The pH scale (0–14) indicates how acidic or basic a solution is.
Q18 — pH Scale · medium · theory
A neutral solution such as pure water has a pH of:
A. 1
B. 7 ✓ Correct
C. 14
D. 0
Solution: Pure water is neutral with pH = 7.
Q19 — pH Scale · medium · theory
A solution with a pH of 3 is:
A. neutral
B. a salt solution
C. basic
D. acidic ✓ Correct
Solution: pH less than 7 means the solution is acidic.
Q20 — pH Scale · medium · theory
The pH of human blood is close to:
A. 0
B. 12 (strongly basic)
C. 2 (strongly acidic)
D. 7.4 (slightly basic) ✓ Correct
Solution: Blood is maintained at a slightly basic pH of about 7.4.
Q21 — Chemical Properties · medium · theory
When a dilute acid reacts with an active metal, the gas evolved is:
A. hydrogen ✓ Correct
B. nitrogen
C. oxygen
D. carbon dioxide
Solution: Acid + metal → salt + hydrogen gas.
Q22 — Chemical Properties · medium · theory
The reaction of an acid with a base to form salt and water is called:
A. displacement
B. oxidation
C. neutralisation ✓ Correct
D. sublimation
Solution: Acid + base → salt + water is a neutralisation reaction.
Q23 — Chemical Properties · medium · theory
Which gas turns lime water milky?
A. Oxygen
B. Hydrogen
C. Ammonia
D. Carbon dioxide ✓ Correct
Solution: Carbon dioxide reacts with lime water to form calcium carbonate, turning it milky.
Q24 — Neutralization · medium · theory
In a neutralisation reaction, an acid and a base react to form:
A. only salt
B. a new acid
C. hydrogen and oxygen
D. salt and water ✓ Correct
Solution: Acid + base → salt + water is the general neutralisation reaction.
Q25 — Neutralization · medium · theory
An antacid tablet relieves acidity in the stomach by:
A. neutralising the excess hydrochloric acid ✓ Correct
B. cooling the stomach
C. producing more acid
D. increasing the acid
Solution: Antacids are mild bases that neutralise the excess stomach acid.
Q26 — Neutralization · medium · theory
Farmers add slaked lime (calcium hydroxide) to acidic soil to:
A. neutralise the excess acidity ✓ Correct
B. add nitrogen
C. kill all crops
D. increase the acidity
Solution: The base neutralises the acid, restoring a pH suitable for crops.
Q27 — Everyday Salts · medium · theory
The chemical name of common table salt is:
A. sodium carbonate
B. sodium bicarbonate
C. sodium chloride ✓ Correct
D. calcium chloride
Solution: Common salt is sodium chloride (NaCl).
Q28 — Everyday Salts · medium · theory
Baking soda used in cooking is chemically:
A. calcium carbonate (CaCO₃)
B. sodium hydrogen carbonate (NaHCO₃) ✓ Correct
C. sodium chloride (NaCl)
D. sodium hydroxide (NaOH)
Solution: Baking soda is sodium hydrogen carbonate, NaHCO₃.
Q29 — Everyday Salts · medium · theory
Plaster of Paris, used to support fractured bones, is obtained by heating:
A. baking soda
B. limestone only
C. gypsum ✓ Correct
D. common salt
Solution: Plaster of Paris is made by heating gypsum (calcium sulphate dihydrate).
Q30 — Everyday Salts · medium · theory
Baking soda is used in baking because on heating it releases ______, which makes the cake rise:
A. hydrogen
B. oxygen
C. carbon dioxide ✓ Correct
D. water vapour only
Solution: On heating, baking soda releases CO₂ gas, which makes the batter fluffy.