MCQ 151
What happens to the pressure of a gas when its volume decreases at constant temperature?
A) It increases.
B) It decreases.
C) It remains constant.
D) It fluctuates.
Answer: A) It increases.
Explanation: According to Boyle’s Law, pressure increases when volume decreases if temperature is held constant.
MCQ 152
What does the term “solubility” refer to?
A) The amount of solute that can dissolve in a solvent
B) The state of matter of a solution
C) The temperature at which a solute dissolves
D) The pressure required for a solute to dissolve
Answer: A) The amount of solute that can dissolve in a solvent.
Explanation: Solubility is the measure of how much solute can dissolve in a specific amount of solvent at a given temperature.
MCQ 153
What occurs during a redox reaction?
A) No electrons are transferred.
B) Only oxidation occurs.
C) Reduction and oxidation occur simultaneously.
D) Only reduction occurs.
Answer: C) Reduction and oxidation occur simultaneously.
Explanation: In a redox reaction, one substance is oxidized (loses electrons) and another is reduced (gains electrons) at the same time.
MCQ 154
Which of the following statements is true regarding exothermic reactions?
A) They absorb heat.
B) They feel cold to the touch.
C) They release heat.
D) They have a positive change in enthalpy.
Answer: C) They release heat.
Explanation: Exothermic reactions release energy, usually in the form of heat, to the surroundings.
MCQ 155
What is formed when an acid reacts with a base?
A) Salt and water
B) Hydrogen gas
C) Carbon dioxide
D) Oxygen gas
Answer: A) Salt and water.
Explanation: The reaction between an acid and a base typically produces a salt and water, known as a neutralization reaction.
MCQ 156
Which of the following is a characteristic of bases?
A) Sour taste
B) Turns red litmus blue
C) Produces H⁺ ions in solution
D) Feels oily
Answer: B) Turns red litmus blue.
Explanation: Bases turn red litmus paper blue and have a bitter taste.
MCQ 157
What is the outcome of a complete combustion reaction?
A) Water and oxygen
B) Water and carbon monoxide
C) Water and carbon dioxide
D) Water and heat only
Answer: C) Water and carbon dioxide.
Explanation: Complete combustion of hydrocarbons results in the production of water (H₂O) and carbon dioxide (CO₂).
MCQ 158
What is the main characteristic of ionic compounds?
A) They have low melting points.
B) They conduct electricity in solid form.
C) They are soluble in non-polar solvents.
D) They form crystals.
Answer: D) They form crystals.
Explanation: Ionic compounds typically form crystal lattices, which contribute to their high melting points and solubility in water.
MCQ 159
Which of the following reactions is an example of a synthesis reaction?
A) 2H₂ + O₂ → 2H₂O
B) CaCO₃ → CaO + CO₂
C) 2Na + Cl₂ → 2NaCl
D) H₂O → H₂ + O₂
Answer: C) 2Na + Cl₂ → 2NaCl.
Explanation: A synthesis reaction involves two or more reactants combining to form a single product.
MCQ 160
What happens during a phase transition from liquid to gas?
A) Energy is released.
B) Energy is absorbed.
C) No energy change occurs.
D) The substance loses mass.
Answer: B) Energy is absorbed.
Explanation: The phase transition from liquid to gas (evaporation) requires energy absorption from the surroundings
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