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Past Questions and Answers

WAEC Chemistry Past Questions And Answers (Objective and Theory)

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WAEC Chemistry Past Questions And Answers (Objective and Theory)


Section A (Objective)


Question: What is the molecular formula for sulfuric acid?



B) H₂SO₃

C) H₂SO₄

D) HS₂O₆

Answer: C) H₂SO₄

Question: Which of the following elements is a noble gas?


A) Chlorine

B) Neon

C) Sodium

D) Potassium

Answer: B) Neon

Question: What is the chemical formula for methane?


A) CH₄

B) CO₂

C) C₂H₆

D) H₂O

Answer: A) CH₄

Question: In the periodic table, what group do alkali metals belong to?


A) Group 1

B) Group 2

C) Group 17

D) Group 18

Answer: A) Group 1

Question: Which gas is responsible for the greenhouse effect?


A) Oxygen

B) Carbon monoxide

C) Nitrogen

D) Carbon dioxide

Answer: D) Carbon dioxide

Question: What is the chemical symbol for gold?


A) Au

B) Ag

C) Fe

D) Cu

Answer: A) Au

Question: Which of the following is an example of a halogen?


A) Fluorine

B) Phosphorus

C) Calcium

D) Iron

Answer: A) Fluorine

Question: What is the pH of a neutral solution?


A) 0

B) 7

C) 14

D) 5

Answer: B) 7

Question: Which element is essential for organic compounds but is not found in inorganic substances?


A) Nitrogen

B) Carbon

C) Oxygen

D) Hydrogen

Answer: B) Carbon

Question: What is the chemical formula for water?


A) H₂O₂

B) CO₂

C) H₂O

D) CH₄

Answer: C) H₂O

Question: Which gas is produced during photosynthesis?


A) Oxygen

B) Nitrogen

C) Carbon dioxide

D) Hydrogen

Answer: A) Oxygen

Question: What is the process of conversion of water vapor into liquid water called?


A) Sublimation

B) Condensation

C) Evaporation

D) Freezing

Answer: B) Condensation

Question: Which of the following is a transition metal?


A) Sodium

B) Zinc

C) Potassium

D) Calcium

Answer: B) Zinc

Question: What is the chemical symbol for silver?


A) Si

B) Ag

C) Al

D) Sr

Answer: B) Ag

Question: In a chemical reaction, what does the arrow represent in a chemical equation?


A) Formation

B) Decomposition

C) Yield

D) Reactants

Answer: C) Yield

Section B (Theory)


Question: Explain the concept of electronegativity and its significance in chemical bonding.


Answer: Electronegativity is the measure of an atom’s ability to attract electrons in a chemical bond. It plays a crucial role in determining the type of bond formed between atoms, whether it’s ionic or covalent. Higher electronegativity leads to a stronger pull on electrons.


Question: Describe the process of oxidation and reduction in chemical reactions.


Answer: Oxidation involves the loss of electrons, while reduction involves the gain of electrons. These reactions occur simultaneously and are integral in redox reactions. The substance losing electrons is oxidized, and the one gaining electrons is reduced.


Question: Discuss the properties and uses of hydrochloric acid (HCl) in industrial and laboratory settings.


Answer: Hydrochloric acid is a strong, corrosive acid. It’s used in industrial processes like pickling, metal cleaning, and pH control. In laboratories, it’s employed for qualitative analysis and preparation of various chemicals.


Question: Explain the principles behind Avogadro’s law and how it relates to the behavior of gases.


Answer: Avogadro’s law states that equal volumes of gases at the same temperature and pressure contain an equal number of molecules. This law is based on the idea that the number of particles (atoms or molecules) is proportional to the volume.


Question: Define the term “catalyst” and provide examples of catalyzed reactions in everyday life.


Answer: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. Examples include enzymes in biological systems and transition metals in industrial processes, enhancing reaction rates.





Add for Neco



Certainly! Here are additional Chemistry questions for the NECO examination:


Section A (Objective)


Question: What is the common name for sodium carbonate?


A) Baking soda

B) Table salt

C) Epsom salt

D) Washing soda

Answer: A) Baking soda

Question: Which gas is evolved when hydrochloric acid reacts with a metal carbonate?


A) Oxygen

B) Carbon dioxide

C) Hydrogen

D) Nitrogen

Answer: B) Carbon dioxide

Question: What is the primary function of the catalyst in a chemical reaction?


A) Initiating the reaction

B) Increasing reaction rate

C) Consuming reactants

D) Producing heat

Answer: B) Increasing reaction rate

Question: Identify the type of bond present in methane (CH₄).


A) Ionic bond

B) Covalent bond

C) Metallic bond

D) Hydrogen bond

Answer: B) Covalent bond

Question: Which of the following is a product of the Haber process?


A) Ammonia

B) Methane

C) Oxygen

D) Sulfuric acid

Answer: A) Ammonia


Section B (Theory)


Question: Discuss the concept of equilibrium in a chemical reaction, providing examples and explaining the factors that influence it.


Answer: Equilibrium in a chemical reaction occurs when the rates of the forward and reverse reactions are equal. Examples include the Haber process and the dissociation of water. Factors like temperature and pressure affect equilibrium.


Question: Describe the structure of an atom, highlighting the roles of protons, neutrons, and electrons. Include information on isotopes.


*Answer: Atoms consist of protons (positively charged), neutrons (neutral), and electrons (negatively charged).

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