SSC CGL Science – Chemical Reactions; Acids, Bases & Salts – Level 3 · Challenge

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SSC CGL Science – Chemical Reactions; Acids, Bases & Salts – Level 3 · Challenge – 8 questions, subject: General Science. Every question has the correct answer with a one-line explanation; tap "Show Answer". Free practice for TNPSC, UPSC, SSC, Bank and RRB exams – Shanmugam IAS Academy, Coimbatore.

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1.  
Balance: NH₃ + O₂ → NO + H₂O. The coefficients (in order) are:

Correct Answer: D [4, 5, 4, 6]

Explanation:

N: 4NH₃ → 4NO; H 12 → 6H₂O; O 4 + 6 = 10 → 5O₂.

2.  
On heating lead nitrate, brown fumes are seen. They are due to:

Correct Answer: D [NO₂]

Explanation:

2Pb(NO₃)₂ → 2PbO + 4NO₂ (brown) + O₂.

3.  
Statement-basedFor CuO + H₂ → Cu + H₂O, which are correct?
I. CuO is reduced.
II. H₂ is the oxidising agent.
III. It is a redox reaction.

Correct Answer: A [Only I and III]

Explanation:

H₂ is oxidised, so it is the reducing agent; CuO is the oxidising agent.

4.  
Arrange in orderArrange in increasing order of pH: milk of magnesia, lemon juice, blood, pure water.

Correct Answer: B [lemon juice < pure water < blood < milk of magnesia]

Explanation:

Answer: lemon juice < pure water < blood < milk of magnesia. ≈ 2–3 < 7 < 7.4 < 10.

5.  
The percentage by mass of water of crystallisation in CuSO₄·5H₂O (Cu = 63.5) is about:

Correct Answer: C [36%]

Explanation:

5 × 18 = 90; 90 ÷ 249.5 × 100 ≈ 36%.

6.  
Match the followingMatch the salt with a use:
P. Bleaching powder Q. Plaster of Paris R. Washing soda S. Baking soda
1. Plaster for fractured bones 2. Disinfecting drinking water 3. Removing permanent hardness of water 4. Antacid

Correct Answer: C [P-2, Q-1, R-3, S-4]

Explanation:

Each salt with its standard use.

7.  
When C₃H₈ + O₂ → CO₂ + H₂O (burning of propane) is balanced, the coefficient of O₂ is:

Correct Answer: A [5]

Explanation:

Answer: 5. C₃H₈ + 5O₂ → 3CO₂ + 4H₂O.

8.  
On strongly heating ferrous sulphate crystals, the products are:

Correct Answer: B [Fe₂O₃, SO₂ and SO₃]

Explanation:

2FeSO₄ → Fe₂O₃ + SO₂ + SO₃ (smell of burning sulphur).

➤ Full notes, shortcuts and every answer explained – SSC CGL 2026 General Science book (₹149): www.shanmugamiasacademy.in/study-materials/ssc-cgl-general-science

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