Chemistry Previous Year Questions with Explanations
Concept revision + 10 clickable questions + detailed explanations
This lesson converts recurring previous-paper concepts into an exam-ready revision set. Question wording is independently rewritten for clarity; explanations are original; and official APPSC, UPSC, SSC and RRB repositories are linked for verification.
Topic Focus
Atomic structure, acids and bases, redox, catalysts, alloys and common compounds.
Rapid Answer Map
| No. | Question focus | Correct answer |
|---|---|---|
| 1 | The atomic number of an element equals the number of: | Protons in the nucleus |
| 2 | A neutral aqueous solution at 25°C has a pH of: | 7 |
| 3 | An acid turns blue litmus: | Red |
| 4 | Oxidation is commonly described as: | Loss of electrons |
| 5 | A catalyst: | Changes reaction rate without being consumed overall |
| 6 | Brass is an alloy mainly of: | Copper and zinc |
| 7 | Bronze is an alloy mainly of: | Copper and tin |
| 8 | Baking soda is: | Sodium hydrogen carbonate |
| 9 | Bleaching powder is commonly represented as: | CaOCl₂ |
| 10 | Noble gases belong to Group: | 18 |
10 Clickable MCQs
The atomic number of an element equals the number of:
Atomic number is the number of protons.
A neutral aqueous solution at 25°C has a pH of:
A neutral solution has pH 7 at 25°C.
An acid turns blue litmus:
Acids turn blue litmus red.
Oxidation is commonly described as:
Oxidation is loss of electrons; reduction is gain of electrons.
A catalyst:
A catalyst provides an alternative pathway with lower activation energy.
Brass is an alloy mainly of:
Brass is primarily copper and zinc.
Bronze is an alloy mainly of:
Bronze is mainly copper and tin.
Baking soda is:
Baking soda is sodium hydrogen carbonate, NaHCO₃.
Bleaching powder is commonly represented as:
Bleaching powder is commonly written as CaOCl₂.
Noble gases belong to Group:
Noble gases are in Group 18 of the periodic table.
Common Exam Traps
Quick Revision Checklist
- 1. Protons in the nucleus — In a neutral atom it also equals the number of electrons.
- 2. 7 — Values below 7 are acidic and above 7 are basic.
- 3. Red — Bases turn red litmus blue.
- 4. Loss of electrons — The two processes occur together in redox reactions.
- 5. Changes reaction rate without being consumed overall — It does not alter the final equilibrium position.
- 6. Copper and zinc — Bronze is mainly copper and tin.
- 7. Copper and tin — Its properties vary with composition.
- 8. Sodium hydrogen carbonate — On heating it releases carbon dioxide.
Frequently Asked Questions
Are these questions copied from coaching websites?
No. Questions are independently rewritten from recurring concepts in official paper repositories and standard sources.
Why is an exact exam year not shown beside every question?
An exam and year are shown only when the source can be checked reliably. This prevents incorrect PYQ attribution.
How should I use this page?
Attempt all questions once, study explanations, revise the answer map, and reattempt after two days.
Official Paper Sources
- APPSC – Question papers and final keys
- APPSC – Question papers of various notifications
- UPSC – Previous question papers
- SSC – Official portal and previous papers
- RRB – Official question/response notices
Source policy: Official repositories establish the tested concepts. Explanations and practice presentation here are original.
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