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NECO Chemistry Questions and Answers for 2025

Published on Jul 1, 2025 • Education

Good day everyone, and welcome to AllCBTs!
My name is Francis, and today we’ll be solving some of the most important and recurring NECO Chemistry Questions and Answers. These are the types of questions that often appear in NECO exams. If you're preparing for NECO 2025, pay close attention, because mastering these will significantly improve your chances of scoring high.

You can watch the full class in the video below:

Question 1: Raw Material for Cement Production

Which of the following is the major raw material for the production of cement?
A. Limestone
B. Gypsum
C. Clay
D. Shell
E. Sand

Correct Answer: A. Limestone
Limestone is the primary raw material used in cement production due to its high calcium carbonate content.

Question 2: Gas that Decolorizes Acidified KMnO₄ Solution

Which gas decolorizes acidified KMnO₄ solution?
A. Carbon(IV) oxide
B. Sulphur(IV) oxide
C. Hydrochloric acid
D. Ammonia
E. Nitrogen(IV) oxide

Correct Answer: B. Sulphur(IV) oxide (SO₂)
SO₂ acts as a reducing agent and decolorizes acidified potassium permanganate by reducing Mn⁷⁺ to Mn²⁺.

Question 3: Compound Reacting with Sodium to Release Hydrogen

Which compound reacts with sodium metal to liberate hydrogen gas?
A. Ethanol
B. Ethanoic acid
C. Methane
D. Ethyne
E. Methanoic acid

Correct Answer: B. Ethanoic acid
Acids react with metals like sodium to release hydrogen gas. Among the options, only ethanoic acid is a true acid.

Question 4: Oxidation Number of Sulphur in H₂SO₄

What is the oxidation number of sulphur in H₂SO₄?
To calculate:

• Hydrogen = +1 × 2 = +2
• Oxygen = -2 × 4 = -8
  Let sulphur = x
  So: 2 + x - 8 = 0
  x = +6

Correct Answer: B. +6

Question 5: Properties of Transition Metals

Which of the following is NOT a property of transition metals?
A. Formation of colored compounds
B. Paramagnetism
C. Variable oxidation states
D. High electronegativity
E. Catalytic ability

Correct Answer: D. High electronegativity
Transition metals generally do not have high electronegativities. The rest are core characteristics of transition elements.

Question 6: Temporary Hardness Removal

Why does boiling remove temporary hardness from water?
A. CO₂ is released
B. Magnesium ions are removed
C. Calcium carbonate is precipitated
D. Sodium hydroxide is added
E. Calcium chloride is formed

Correct Answer: A. CO₂ is released
Boiling causes carbon dioxide to escape, which reduces the bicarbonate content, softening the water.

Question 7: Example of a Strong Electrolyte

(The subtitle preview ends here, so full data for this question may be unavailable, but you can continue with similar structure for rest of questions.)

Watch more educational videos and past questions: https://youtube.com/@allcbts

Final Tips to Pass NECO Chemistry 2025

1. Master Common Concepts – Redox reactions, periodic table trends, acids and bases, and chemical bonding are frequently tested.
2. Practice With Past Questions – NECO often repeats or rephrases previously asked questions.
3. Understand, Don’t Just Memorize – Try to reason through questions logically.
4. Watch Video Tutorials – AllCBTs offers comprehensive Chemistry breakdowns on YouTube.

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