Key Science Questions and Answers
01. Which part of the eye determines its color?
Answer- Iris
02. How does increasing altitude affect atmospheric pressure?
Answer- Atmospheric pressure decreases
03. What controls the amount of light entering the eye?
Answer- Pupil
04. Which device converts sound energy into electrical energy?
Answer- Microphone (Invented by Emile Berliner)
05. Which device converts chemical energy into electrical energy?
Answer- Electric cell
06. Why do chameleons change color?
Answer- They change color to cope with heat
07. Give three examples of gas diffusion.
Answer- Aroma of food, fragrance of incense sticks, and scent of perfume
08. On which effect of electric current do electric motors, telephones, telegraphs, and electric bells operate?
Answer- Magnetic effect
09. Why does a drop of oil spread over water?
Answer- Due to the high surface tension of water
10. What causes a liquid drop to be spherical?
Answer- Surface tension
11. What is used to determine the purity of a metal?
Answer- Archimedes’ principle
12. What is the energy generated during a nuclear fission reaction used for?
Answer- Generating electricity
13. Why does water boil at a lower temperature in the mountains?
Answer- Atmospheric pressure is lower in the mountains
14. A fuse wire is a thin wire made of an alloy of ———-?
Answer- Tin and lead
15. Why do clouds float in the atmosphere?
Answer- Due to low density
16. Which are the only two tissues that do not receive oxygen from the blood?
Answer- Nails and cornea
17. What is the smallest bone in the human body? Answer- Steppes
18. On what principle does a refrigerator operate?
Answer- The principle of liquid evaporation
19. What does the time period of a pendulum depend on?
Answer- Length
20. On what principle does a washing machine operate?
Answer- Centrifugation
21. Which disease is caused by a deficiency of Vitamin B-1?
Answer- Beriberi
22. Between what is the ‘Nichrome’ heating element of an electric iron placed?
Answer- Mica
23. Who was the first to measure the speed of light?
Answer- Rømer
24. Why does a cyclist lean while taking a turn?
Answer- He leans so that the center of gravity remains within the base, preventing him from falling.
25. How many isotopes does hydrogen have?
Answer- Three (Protium, Deuterium, and Tritium)