Acids, Bases & Salts — BPSC Previous Year Questions
8 questions from past BPSC papers, each with the correct answer and an
explanation of why. Free to read — no signup.
How often it has appeared
Paper
67
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71
70Re
Total
Acids, Bases & Salts
0
4
2
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9
Questions
63rd Pre · 2018
pH of pure water at 25°C is:
0
7
10
14
64th Pre · 2018
Chemical formula of baking soda is:
Na₂CO₃
NaHCO₃
CaCO₃
NaOH
67th Pre · 2022
Bee stings can be relieved by applying:
Vinegar
Lemon juice
Baking soda solution
Hot water
Why: Bee sting acidic (formic acid); neutralised by mild base.
65th Pre · 2019
Bleaching powder (CaOCl₂) is prepared by passing chlorine over:
Quicklime
Slaked lime (Ca(OH)₂)
Limestone
NaOH
68th Pre · 2023
Which acid is described as HOOC-COOH?
Carbonic acid
Oxalic acid
Acetic acid
Tartaric acid
Why: Oxalic acid.
68th Pre · 2023
Which test tube turns red litmus to blue?
Distilled water
Acid
Base
Saline solution
Why: Bases turn red litmus blue.
68th Pre · 2023
Why does dry HCl gas not change the colour of dry litmus paper?
HCl gas acts as dehydrating agent
Blue litmus becomes dry in presence of HCl
No H₃O⁺ ions present; litmus changes only with H₃O⁺
Dry HCl is neutral
Why: Hydronium ions are needed.
70th Pre · 2024
Constituents of a soda-acid fire extinguisher?
Conc. H₂SO₄ + Aluminium sulphate
Dil. H₂SO₄ + Sodium carbonate
Dil. H₂SO₄ + Sodium bicarbonate
Conc. H₂SO₄ + Sodium carbonate
Why: Dil. H₂SO₄ + NaHCO₃.
Mains-style questions on this topic
Descriptive questions from past papers. There is no single correct option — practise
writing the answer, then check your structure against the syllabus.
66th Mains GS-1 · 2020
Define pH. List three uses of pH in daily life with examples.
Study these topics in order, and remember them
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