Level 1
Physical Science MCQs set 3 for Pakistan Coast Guard / Maritime Security Everyday Science — 20 solved questions.
Q1. Which of the following gases is used in cigarette lighters?
Answer: Butane
Explanation: Butane (C₄H₁₀) is the fuel used in most disposable and refillable cigarette lighters because it is easily liquefied under moderate pressure and vaporizes readily at room temperature.
Q2. Which of the following elements is not essential for plants?
Answer: Iodine
Explanation: Iodine is an essential micronutrient for humans and animals (needed for thyroid hormones) but is not required for plant growth; plants do not produce iodine-dependent compounds.
Q3. Which element is most abundant in the Universe?
Answer: Hydrogen
Explanation: Hydrogen is the scientifically accurate choice. The concept tested here is core everyday science for MDCAT, ECAT, and general ability papers.
Q4. Which of these has the lowest pH?
Answer: Gastric Juice
Explanation: Gastric juice has a pH of approximately 1.5-3.5, making it the most acidic body fluid, far more acidic than saliva (6.5-7.5), bile (~7.8), or pancreatic juice (~8.3).
Q5. A loudspeaker changes ______ energy into sound energy.
Answer: Electrical
Explanation: A loudspeaker converts electrical energy (alternating current signals) into mechanical vibrations of a cone/diaphragm, which then produce sound waves in the surrounding air.
Q6. The branch of chemistry that deals with the study of compounds containing carbon is called:
Answer: Organic chemistry
Explanation: Organic chemistry is the branch dedicated to the study of carbon-containing compounds, including their structure, properties, reactions, and synthesis.
Q7. Which of the following minerals is most resistant to chemical weathering?
Answer: Quartz
Explanation: Quartz (SiO₂) is highly resistant to chemical weathering due to its strong covalent Si-O bonds and lack of cleavage planes, making it the most stable common mineral at Earth's surface.
Q8. Refractometer is used to determine the concentration of solutes in a solution such as:
Answer: Sugars
Explanation: A refractometer measures the refractive index of a liquid, which correlates with solute concentration; it is widely used in food science to measure sugar (Brix) levels in solutions.
Q9. Television signals are converted into light signals for transmission through:
Answer: Optical fiber
Explanation: Optical fibre cables transmit data as pulses of light (converted from electrical signals), enabling high-speed, long-distance telecommunication with minimal signal loss.
Q10. The lightest metal is:
Answer: Lithium
Explanation: Lithium is the lightest metal with a density of only 0.534 g/cm³ and atomic mass 6.941; it is so light it can float on water.
Q11. What is the SI unit of Charge?
Answer: Coulomb
Explanation: The SI unit of electric charge is the Coulomb (C), defined as the charge transported by a current of one ampere in one second (1 C = 1 A·s).
Q12. The cosmic microwave background radiation comes from:
Answer: The Big Bang
Explanation: The cosmic microwave background (CMB) radiation is the thermal afterglow of the Big Bang, released about 380,000 years after the event when the universe cooled enough for atoms to form.
Q13. Which of the following devices is used to step up or step down the voltage of an alternating current?
Answer: Transformer
Explanation: A transformer uses electromagnetic induction to increase (step up) or decrease (step down) the voltage of an alternating current, based on the ratio of turns in its primary and secondary coils.
Q14. A lower pH value means:
Answer: Stronger acid
Explanation: The pH scale runs from 0 to 14; lower pH values indicate a higher concentration of hydrogen ions (H⁺), meaning a stronger acid - pH 1 is far more acidic than pH 6.
Q15. Which of the following is Right for sound?
Answer: Sound cannot travel through a vacuum
Explanation: Sound is a mechanical wave that requires a physical medium to travel; it cannot propagate through a vacuum because there are no particles to transmit the compressions and rarefactions.
Q16. Two parallel wires carrying currents in the same direction attract each other because of:
Answer: Magnetic forces between them
Explanation: Parallel wires carrying currents in the same direction create magnetic fields that interact - by the right-hand rule and Ampere's force law, the magnetic force between them is attractive.
Q17. The velocity of wind is measured by an:
Answer: Anemometer
Explanation: An anemometer measures wind speed and direction; it typically consists of rotating cups whose speed of rotation is proportional to wind velocity.
Q18. Which group of elements in the periodic table shows the highest first ionization potential? Elements in the:
Answer: Right-hand top corner
Explanation: First ionization energy increases across a period (left to right) and decreases down a group; elements in the top-right corner (noble gases/halogens like He, Ne, F) have the highest values.
Q19. Isotopes of an element have the same number of:
Answer: Protons
Explanation: Isotopes of the same element have the same number of protons (and electrons) - which defines their chemical identity - but differ in the number of neutrons, giving different mass numbers.
Q20. The study of energy production in living bodies is called:
Answer: Bioenergetics
Explanation: Bioenergetics is the branch of biology that studies how living organisms transform, store, and use energy through metabolic processes such as cellular respiration and photosynthesis.