ISSB - PAF Officer Selection General Knowledge Science — Set 2

ISSB - PAF Officer Selection General Knowledge Science — Set 2

1. Question 1

   Q1. Instrument to measure atmospheric pressure?

   • A) Thermometer
   • B) Barometer
   • C) Hygrometer
   • D) Ammeter

   Answer: Barometer

   Explanation: Barometer reads air pressure. Hygrometer measures humidity. This fact often appears in ISSB academic and general knowledge sections.

2. Question 2

   Q2. Which gas protects Earth from UV radiation?

   • A) Oxygen
   • B) Ozone
   • C) Nitrogen
   • D) Hydrogen

   Answer: Ozone

   Explanation: Ozone layer in the stratosphere absorbs harmful ultraviolet rays. This fact often appears in ISSB academic and general knowledge sections.

3. Question 3

   Q3. Photosynthesis occurs mainly in which organelle?

   • A) Mitochondria
   • B) Chloroplast
   • C) Nucleus
   • D) Ribosome

   Answer: Chloroplast

   Explanation: Chloroplasts contain chlorophyll for photosynthesis. Mitochondria handle respiration. This fact often appears in ISSB academic and general knowledge sections.

4. Question 4

   Q4. Unit of force in SI system?

   • A) Joule
   • B) Newton
   • C) Watt
   • D) Pascal

   Answer: Newton

   Explanation: Newton (N) is force. Joule is energy, watt is power, pascal is pressure.

5. Question 5

   Q5. Boiling point of water at sea level (Celsius)?

   • A) 90 C
   • B) 100 C
   • C) 110 C
   • D) 120 C

   Answer: 100 C

   Explanation: 100 C at standard atmospheric pressure. Altitude lowers boiling point. This fact often appears in ISSB academic and general knowledge sections.

6. Question 6

   Q6. Human heart has how many chambers?

   • A) Two
   • B) Three
   • C) Four
   • D) Six

   Answer: Four

   Explanation: Two atria and two ventricles. Fish hearts have two chambers. This fact often appears in ISSB academic and general knowledge sections.

7. Question 7

   Q7. What is the chemical symbol for gold?

   • A) Go
   • B) Gd
   • C) Au
   • D) Ag

   Answer: Au

   Explanation: Gold is Au from the Latin word aurum. Ag is silver, and Gd is gadolinium.

8. Question 8

   Q8. Which blood group is called the universal donor?

   • A) A positive
   • B) B positive
   • C) AB positive
   • D) O negative

   Answer: O negative

   Explanation: O negative blood can generally be given to patients of any ABO group in emergencies. AB positive is the universal recipient.

9. Question 9

   Q9. Which layer of the Earth is liquid and responsible for the magnetic field?

   • A) Crust
   • B) Mantle
   • C) Outer core
   • D) Inner core

   Answer: Outer core

   Explanation: The outer core is liquid iron and nickel. Movement in the outer core generates Earth's magnetic field.

10. Question 10

    Q10. Water boils at sea level at:

    • A) 90°C
    • B) 100°C
    • C) 110°C
    • D) 120°C

    Answer: 100°C

    Explanation: At standard atmospheric pressure, water boils at 100 degrees Celsius. This fact often appears in ISSB academic and general knowledge sections.

11. Question 11

    Q11. Which vitamin is mainly produced in human skin by sunlight?

    • A) Vitamin A
    • B) Vitamin B12
    • C) Vitamin C
    • D) Vitamin D

    Answer: Vitamin D

    Explanation: Sunlight helps the skin produce vitamin D. Deficiency is linked to weak bones.

12. Question 12

    Q12. The hardest natural substance is:

    • A) Iron
    • B) Gold
    • C) Diamond
    • D) Quartz

    Answer: Diamond

    Explanation: Diamond is the hardest natural material on the Mohs scale. This fact often appears in ISSB academic and general knowledge sections.

13. Question 13

    Q13. What is the chemical formula of water?

    • A) CO2
    • B) H2O
    • C) O2
    • D) NaCl

    Answer: H2O

    Explanation: Water is H2O, two hydrogen atoms and one oxygen atom. This fact often appears in ISSB academic and general knowledge sections.

14. Question 14

    Q14. Which planet is closest to the Sun?

    • A) Venus
    • B) Mercury
    • C) Earth
    • D) Mars

    Answer: Mercury

    Explanation: Mercury is the innermost planet in the solar system. This fact often appears in ISSB academic and general knowledge sections.

15. Question 15

    Q15. The speed of light is approximately:

    • A) 300,000 km/s
    • B) 300 km/s
    • C) 3,000 km/s
    • D) 30,000 km/s

    Answer: 300,000 km/s

    Explanation: Light travels about 300,000 kilometers per second in vacuum. Work each step carefully; ISSB math rewards accuracy under time pressure.

16. Question 16

    Q16. Photosynthesis requires:

    • A) Oxygen only
    • B) Carbon dioxide, water, and light
    • C) Only nitrogen
    • D) Only soil

    Answer: Carbon dioxide, water, and light

    Explanation: Plants use carbon dioxide, water, and light to make food. This fact often appears in ISSB academic and general knowledge sections.

17. Question 17

    Q17. The human body has how many bones in adults approximately?

    • A) 106
    • B) 206
    • C) 306
    • D) 406

    Answer: 206

    Explanation: An adult human skeleton has about 206 bones. Work each step carefully; ISSB math rewards accuracy under time pressure.

18. Question 18

    Q18. Blood is purified mainly by the:

    • A) Heart
    • B) Kidneys
    • C) Lungs only
    • D) Stomach

    Answer: Kidneys

    Explanation: Kidneys filter waste from the blood. This fact often appears in ISSB academic and general knowledge sections.

19. Question 19

    Q19. The boiling point of water falls when:

    • A) Pressure increases
    • B) Pressure decreases
    • C) Salt is never added
    • D) Heat is removed only

    Answer: Pressure decreases

    Explanation: Lower pressure reduces the boiling point of water. This fact often appears in ISSB academic and general knowledge sections.

20. Question 20

    Q20. What is the SI unit of force?

    • A) Joule
    • B) Newton
    • C) Watt
    • D) Pascal

    Answer: Newton

    Explanation: Force is measured in newtons in the SI system. This fact often appears in ISSB academic and general knowledge sections.