MCQ Collection
Pakistan MCQs
Practice Pakistan questions with answers and explanations.
Choose an option to check your answer.
Correct Answer: B. It increases collision frequency and usually increases rate
Explanation:
More particles per volume collide more often.
The exact effect is described by the rate law.
Choose an option to check your answer.
Correct Answer: B. An acid that ionizes essentially completely in water
Explanation:
Strength refers to extent of ionization, not concentration.
Strong acids produce hydronium ions nearly completely.
Choose an option to check your answer.
Correct Answer: C. An acid that ionizes only partially in water
Explanation:
Weak-acid solutions contain both ionized and unionized forms.
They establish an equilibrium in water.
Choose an option to check your answer.
Correct Answer: D. Negative logarithm of hydrogen-ion activity or approximate concentration
Explanation:
For dilute solutions, pH≈-log[H+].
Lower pH generally means greater acidity.
Choose an option to check your answer.
Correct Answer: A. Liver
Explanation:
The liver produces bile continuously.
The gallbladder stores and concentrates it.
Choose an option to check your answer.
Correct Answer: A. Negative logarithm of hydroxide-ion concentration
Explanation:
For dilute aqueous solutions, pOH=-log[OH-].
At 25°C, pH+pOH≈14.
Choose an option to check your answer.
Correct Answer: B. -40 kJ
Explanation:
Use ΔG=ΔH-TΔS.
ΔG=-100-300(-0.20)=-40 kJ.
Choose an option to check your answer.
Correct Answer: C. A solution that resists large pH changes
Explanation:
Buffers contain a weak acid-base pair.
They consume added H+ or OH-.
Choose an option to check your answer.
Correct Answer: C. -30 kJ
Explanation:
Use ΔG=50-400(0.20).
ΔG=50-80=-30 kJ.
Choose an option to check your answer.
Correct Answer: D. Reaction of an acid and base to form water and a salt
Explanation:
In many aqueous neutralizations, H+ and OH- form water.
The remaining ions form a salt.
Choose an option to check your answer.
Correct Answer: D. 4
Explanation:
For the 1:1 equation, Kc=[B]/[A].
Kc=0.80/0.20=4.
Choose an option to check your answer.
Correct Answer: A. A substance changing color over a characteristic pH range
Explanation:
Acid-base indicators have differently colored protonated and deprotonated forms.
They help identify titration endpoints.
