MCQ 101
What does the term “limiting reagent” refer to in a chemical reaction?
A) The reactant that is present in excess
B) The reactant that determines the amount of product formed
C) The product that limits the reaction
D) The catalyst used in the reaction
Answer: B) The reactant that determines the amount of product formed.
Explanation: The limiting reagent is the reactant that is completely consumed first, limiting the extent of the reaction.
MCQ 102
What is formed when sodium reacts with water?
A) Sodium hydroxide and hydrogen gas
B) Sodium chloride and oxygen
C) Sodium bicarbonate and water
D) Sodium oxide and hydrogen gas
Answer: A) Sodium hydroxide and hydrogen gas.
Explanation: The reaction of sodium with water produces sodium hydroxide (NaOH) and hydrogen gas (H₂).
MCQ 103
Which of the following laws states that the ratio of the masses of elements in a compound is always the same?
A) Law of Multiple Proportions
B) Law of Definite Proportions
C) Law of Conservation of Mass
D) Dalton’s Law
Answer: B) Law of Definite Proportions.
Explanation: This law asserts that a chemical compound always contains its constituent elements in a fixed mass ratio.
MCQ 104
What happens during a chemical reaction according to the Law of Conservation of Mass?
A) Mass can be created or destroyed.
B) The total mass of reactants equals the total mass of products.
C) Only some elements are conserved.
D) Energy is lost as heat.
Answer: B) The total mass of reactants equals the total mass of products.
Explanation: This law states that in a closed system, mass remains constant during a chemical reaction.
MCQ 105
What type of reaction is represented by the equation: 2H₂ + O₂ → 2H₂O?
A) Single replacement
B) Decomposition
C) Synthesis
D) Double replacement
Answer: C) Synthesis.
Explanation: This reaction shows two reactants (hydrogen and oxygen) combining to form a single product (water).
MCQ 106
Which of the following is an example of a physical change?
A) Iron rusting
B) Water boiling
C) Wood burning
D) Baking a cake
Answer: B) Water boiling.
Explanation: Boiling water is a physical change as it involves a change in state but not a change in chemical composition.
MCQ 107
When balancing a chemical equation, what should be done first?
A) Balance the most complex molecule.
B) Balance the elements present in only one reactant and one product.
C) Balance hydrogen and oxygen last.
D) Use fractions if necessary.
Answer: B) Balance the elements present in only one reactant and one product.
Explanation: It’s usually best to start with elements that appear in only one reactant and one product before moving to others.
MCQ 108
What is the process called when a solid turns directly into a gas?
A) Condensation
B) Sublimation
C) Evaporation
D) Freezing
Answer: B) Sublimation.
Explanation: Sublimation is the process where a solid changes directly into a gas without passing through a liquid state.
MCQ 109
What does the term “aqueous solution” refer to?
A) A solution containing gas
B) A solution in which water is the solvent
C) A solution containing solid particles
D) A solution that conducts electricity
Answer: B) A solution in which water is the solvent.
Explanation: An aqueous solution is one in which water is used as the solvent for dissolving substances.
MCQ 110
Which of the following compounds is formed through ionic bonding?
A) CO₂
B) H₂O
C) NaCl
D) CH₄
Answer: C) NaCl.
Explanation: Sodium chloride (NaCl) is formed through ionic bonding between sodium (Na) and chlorine (Cl) ions.
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