Q23. Why mountaineers carry oxygen cylinders with them, while climbing high mountains?
Q24. Why do you feel suffocated in a closed space after sometime if a material is burning?
Q25. Why does the transparent glass of windows appear hazy if not wiped off for long time?
Q26. Why is it not advisable to breathe through our mouth?
Q27. Dia took an open mouth bottle and dips it upside down into the water. Will the water move inside the bottle? Give a reason to support your answer.
Q28. When an open mouth bottle is tilted and dipped into water, bubbles coming out of the bottle was observed. Explain the reason.
Q29. How carbon dioxide enters the atmosphere?
Q30. List two uses of wind energy.
Q31. How does weathercock (Wind vane) work?
Q32. Is it possible to light up a candle on the moon? Give reason.
Q33. Earthworms come out of the soil during heavy rains. Why?
Q34. Why does the candle go off after some time when we cover it with a glass tumbler?
Q35. What happens when air comes in contact with a cool surface?
Q36. Why long chimneys are preferred in factories?
Q37. What is the role of fine hair and mucus inside the nose?
Q38. Why do policemen regulating traffic at a crowded crossing wear a mask to cover his face?