Cause and Effect Reasoning MCQs for MDCAT Practice

Science Reasoning section, Cause and Effect Reasoning chapter. Sample questions from past PMC papers.

1. Question 1
   If magnesium burns in air, forming a white ash, what does this indicate?
   • A.Physical change
   • B.Loss of mass
   • C.Chemical reaction with oxygen
   • D.Freezing point of magnesium
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2. Question 2
   A person inhales carbon monoxide. What makes it dangerous?
   • A.It causes immediate suffocation
   • B.It binds to hemoglobin more strongly than oxygen
   • C.It burns the lungs
   • D.It forms water in the blood
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3. Question 3
   If 10 clothes are dried up together in 1 hour, in how many hours can 20 clothes be dried up together?
   • A.1 hour
   • B.2 hours
   • C.3 hours
   • D.4 hours
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4. Question 4
   A battery is connected to a resistor. What happens when resistance increases?
   • A.Current increases
   • B.Voltage decreases
   • C.Current decreases
   • D.Battery explodes
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5. Question 5
   The radius of the second orbit in hydrogen atom is
   • A.Greater than the first orbit
   • B.Equal to the first orbit
   • C.Less than the first orbit
   • D.None of these
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6. Question 6
   The compounds BrCl and BrI melt at –66°C and 42°C, respectively.What is the best explanation for this difference in melting points?
   • A.The Br-I covalent bond is stronger than the Br−Cl covalent bond
   • B.Chlorine is more reactive than iodine so chlorine breaks away from bromine more readily than iodine
   • C.The forces between BrI molecules are stronger than the forces between BrCl molecules
   • D.Iodide ions are larger than chloride ions so bromide ions form stronger ionic bonds with iodide ions than with chloride ions
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7. Question 7
   A pendulum clock runs slow in summer. Why?
   • A.Expansion increases its length
   • B.Heat speeds up motion
   • C.Weight changes
   • D.Air resistance is more
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8. Question 8
   Why are safety goggles used in labs?
   • A.They correct vision
   • B.They are fashionable
   • C.They protect from splashes and fumes
   • D.They detect color change
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