MCQ 111
What does the term “activation energy” refer to?
A) The energy released during a reaction
B) The energy needed to start a reaction
C) The energy available after a reaction
D) The energy lost to the environment
Answer: B) The energy needed to start a reaction.
Explanation: Activation energy is the minimum energy required to initiate a chemical reaction.
MCQ 112
What is the main characteristic of exothermic reactions?
A) They absorb energy.
B) They release energy.
C) They require constant heat.
D) They do not involve energy changes.
Answer: B) They release energy.
Explanation: Exothermic reactions release energy in the form of heat or light to the surroundings.
MCQ 113
Which law describes the behavior of gases under varying pressures and temperatures?
A) Charles’s Law
B) Boyle’s Law
C) Ideal Gas Law
D) Avogadro’s Law
Answer: C) Ideal Gas Law.
Explanation: The Ideal Gas Law (PV = nRT) relates pressure (P), volume (V), temperature (T), and the amount of gas (n).
MCQ 114
Which of the following describes a double replacement reaction?
A) A + B → C
B) A + BC → AC + B
C) AB + CD → AD + CB
D) A → B + C
Answer: C) AB + CD → AD + CB.
Explanation: In a double replacement reaction, two compounds exchange ions to form two new compounds.
MCQ 115
What is produced during the electrolysis of water?
A) Oxygen and hydrogen gases
B) Carbon dioxide and water
C) Sodium and chloride
D) Nitrogen and ammonia
Answer: A) Oxygen and hydrogen gases.
Explanation: Electrolysis of water splits it into hydrogen gas and oxygen gas.
MCQ 116
What happens to the temperature of a substance during a phase change?
A) It increases steadily.
B) It decreases steadily.
C) It remains constant.
D) It fluctuates wildly.
Answer: C) It remains constant.
Explanation: During a phase change, the temperature of a substance remains constant while energy is added or removed.
MCQ 117
What is the primary product of the combustion of fossil fuels?
A) Methane
B) Water
C) Carbon monoxide
D) Carbon dioxide
Answer: D) Carbon dioxide.
Explanation: The combustion of fossil fuels primarily produces carbon dioxide (CO₂) along with water (H₂O) and energy.
MCQ 118
What is a characteristic of metallic bonding?
A) Electrons are transferred between atoms.
B) Electrons are shared between specific atoms.
C) Electrons are delocalized and shared among many atoms.
D) Electrons are fixed in place.
Answer: C) Electrons are delocalized and shared among many atoms.
Explanation: In metallic bonding, electrons are free to move throughout the structure, contributing to conductivity.
MCQ 119
In a chemical reaction, which of the following represents the reactants?
A) The products formed after the reaction
B) The starting materials that undergo change
C) The energy released
D) The catalyst used in the reaction
Answer: B) The starting materials that undergo change.
Explanation: Reactants are the substances that undergo change during a chemical reaction to form products.
MCQ 120
Which type of reaction occurs when an acid reacts with a base?
A) Synthesis
B) Decomposition
C) Neutralization
D) Redox
Answer: C) Neutralization.
Explanation: A neutralization reaction occurs when an acid reacts with a base to produce water and a salt.
Leave a comment