Mastery

Pressure, Winds, Storms, and Cyclones — Mastery

30 questions 30 min Full-chapter mastery

Q1. Megha carries her school bag using broad straps while Pawan uses narrow straps; both bags weigh the same. Megha feels more comfortable mainly because
- A. The broad strap spreads the same weight over a larger shoulder area, producing less pressure on her shoulders
- B. The broad strap is made of a lighter material than the narrow one
- C. Megha is physically stronger than Pawan
- D. The narrow strap increases the total weight of the bag
Q2. A book exerts a force of 100 N perpendicularly on a table over an area of 2 m^2. The pressure exerted by the book on the table is
- A. 200 N/m^2
- B. 100 N/m^2
- C. 2 N/m^2
- D. 50 N/m^2
Q3. A sharpened knife cuts vegetables more easily than a blunt one mainly because
- A. A sharp knife is heavier than a blunt knife
- B. Sharpening a knife changes the material from iron to steel
- C. A blunt knife is colder than a sharp knife
- D. A sharp edge has a smaller area, so the same applied force produces a much higher pressure on the vegetable
Q4. Carrying a water-filled bucket by its broad plastic handle is more comfortable than carrying it by a thin metal wire of the same length, because
- A. The plastic handle reduces the weight of water in the bucket
- B. Metal handles are always slippery
- C. A thin wire makes the bucket lighter as it cuts the air
- D. A broad handle increases the area of contact with the palm, reducing the pressure on the hand for the same weight
Q5. In Activity 6.1, water is poured into two connected pipes of unequal diameter, each having an identical balloon fitted at its lower end. When the water reaches the same level in both pipes, the bulges of the two balloons are observed. The expected result is
- A. The balloon on the wider pipe bulges out much more, because it holds more water
- B. Only the balloon on the narrower pipe bulges; the wider one does not bulge at all
- C. Neither balloon bulges, since water has not spilled
- D. Both balloons bulge equally, because the water column above each is of the same height
Q6. In Activity 6.2 with a punctured plastic bottle full of water, water spurts most strongly out of the
- A. Hole near the top of the bottle
- B. Hole at the middle of the bottle
- C. Hole near the bottom of the bottle
- D. Mouth of the bottle, never from the holes
Q7. Which of the following sets of gases best describes the major composition of the Earth's atmosphere as listed in Chapter 6?
- A. Hydrogen, helium and neon
- B. Carbon monoxide, methane and ammonia
- C. Nitrogen, oxygen, argon and carbon dioxide
- D. Chlorine, ozone and sulphur dioxide
Q8. The air column above a 15 cm x 15 cm area exerts a force of about 2250 N. Taking g ~ 10 m/s^2, this force is equivalent to placing on that area a mass of about
- A. 225 kg
- B. 22.5 kg
- C. 2.25 kg
- D. 22500 kg
Q9. Along a coast on a summer afternoon, a cool sea breeze blows from the sea towards the land mainly because
- A. The sea heats up faster than the land in the day
- B. Land heats up faster than the sea in the day; warm air over land rises, creating a low-pressure area that draws cooler air in from the sea
- C. The Moon's gravity pulls sea air landward only during the afternoon
- D. Sea water becomes lighter than land air after noon
Q10. When a thin strip of paper is held near the lower lip and air is blown horizontally over its upper surface, the free end of the strip rises up. The best explanation is
- A. Blowing pushes the paper down, so it must bounce back up
- B. The blown breath is warm, so it lifts the paper by convection
- C. High-speed air over the upper surface creates a region of lower pressure there; the higher pressure below pushes the strip up
- D. Static charges on the paper are attracted to the mouth
Q11. Storms occur frequently in hot and humid tropical countries like India mainly because
- A. Plenty of warm, moist air is available for rapid rising and cloud formation
- B. Tropical countries lie close to the magnetic poles of the Earth
- C. Hot countries always have very strong sea breezes throughout the day
- D. Tropical countries get heavier seasonal snowfall than other regions
Q12. Inside a tall thundercloud, what creates the static electric charges that eventually cause lightning?
- A. Direct heating of the cloud by sunlight
- B. Rapid up and down movement of winds inside the cloud, causing rubbing of water droplets and ice particles against one another
- C. The Earth's magnetic field aligning the water molecules
- D. Sound waves from earlier thunder ionising the air
Q13. Anita is caught in an open field during a thunderstorm with frequent lightning. Which of the following actions is INCORRECT?
- A. Find a low-lying open area and crouch down on the ground
- B. Move away from tall trees and other tall objects
- C. Lie flat on the ground with arms and legs stretched out
- D. Avoid using an umbrella with a metallic rod
Q14. The cyclone Amphan that hit India in May 2020 had a peak wind speed of about
- A. 27 km/h
- B. 270 km/h
- C. 70 km/h
- D. 2700 km/h
Q15. Modern cyclone warnings in India are made much more reliable by the use of
- A. Hot-air balloons released from the coast
- B. Ground-based radio receivers only
- C. Hand-held thermometers carried by fishermen
- D. Weather satellites that track and help predict the path of cyclones
Q16. A Class 8 student writes: 'The eye of a cyclone is the most stormy and destructive part of the cyclone.' Which of the following is the MOST effective way for a teacher to correct this misconception?
- A. Tell the student to memorise the True/False answer key without discussion
- B. Mark the answer wrong and move to the next chapter without explanation
- C. Show satellite images of a real cyclone and explain that at the eye the winds are calm while the strongest winds and heaviest rain occur in the spiral region around the eye
- D. Ignore the misconception because the textbook does not address it directly
Q17. Before performing Activity 6.6 (blowing between two suspended balloons) with her class, a Science teacher first asks each child to PREDICT what will happen and write it down. The MOST important pedagogical purpose of this 'predict-then-observe' step is to
- A. Save time during the actual demonstration
- B. Make the activity look more scientific to school inspectors
- C. Ensure that all students get the same prediction before the demonstration
- D. Surface students' prior ideas and let any mismatch with the observation drive meaningful conceptual change
Q18. A Class 8 teacher wants to introduce lightning-safety rules. Which of the following is the BEST sequence of teaching steps grounded in Chapter 6?
- A. Make students copy a long list of safety rules into their notebooks first, then discuss
- B. Have students draw decorative posters of lightning before any discussion of physics or safety
- C. Begin with the lightning conductor's construction details and skip the personal-safety rules
- D. Show a short cyclone or thunderstorm video, ask students to list their home rules, then compare these with NCERT's rules (low-lying open area, away from tall objects, no metallic-rod umbrella, etc.) and discuss reasons
Q19. From Megha and Pawan's school-bag example, pressure is introduced through the relation: same force on a smaller area gives a higher pressure. Which everyday observation does NOT fit this relation?
- A. A sharp knife cuts a vegetable more easily than a blunt one
- B. A wide tractor tyre sinks less in a soft field than a narrow car tyre
- C. A heavy load is easier to carry on a flat plank than on a thin rope of the same length
- D. A glass of water becomes warmer if it is stirred for a longer time
Q20. While defining pressure as force per unit area, for the pressure formula P = F/A to apply correctly
- A. The force must act perpendicular to the surface; only the perpendicular component contributes to pressure on that surface
- B. The force must act parallel to the surface
- C. The force must always act vertically downwards, regardless of the surface
- D. Pressure has no relation with the direction in which the force is applied
Q21. During a severe storm, the tin roof of a weak roadside shed is sometimes blown OFF (lifted up and away). The best explanation using Chapter 6 ideas is
- A. Heavy rain on top of the roof makes it lighter than the air inside, so it floats away
- B. High-speed winds over the roof create a low-pressure region above it, while the air pressure inside the shed remains higher; the upward pressure difference lifts the roof off
- C. Wind moves the Earth beneath the shed, so the roof tears loose
- D. Strong winds increase the air pressure above the roof and crush it downwards
Q22. While studying cyclone formation, students ask why the inward-rushing air does not just travel in a straight line towards the centre but instead spirals into a spinning cyclone. The correct reason given in Chapter 6 is
- A. The Moon's gravity twists the air into a spiral pattern
- B. Magnetic fields in the ocean force the air to spin
- C. Ocean currents drag the air in circles
- D. The rotation of the Earth deflects the moving air, causing it to spin around the central low-pressure region
Q23. A few months after a severe cyclone, farmers in an Odisha coastal village find that crops in fields near the shore are growing much more poorly than usual. The most likely Chapter 6 reason is
- A. Cyclones permanently change the soil into rocks
- B. The continuous noise of the storm has driven away earthworms
- C. Lightning during the cyclone has burnt all the seeds in the ground
- D. Seawater pushed inland by the storm has left salt in the soil, reducing its fertility
Q24. Inside a tall cloud, as warm moist air rises higher and higher, the water droplets it carries
- A. Continuously evaporate back into water vapour
- B. Become hotter and eventually catch fire
- C. Combine with nitrogen to form a new gas
- D. Encounter very low temperatures at high altitudes and may freeze into ice particles
Q25. During a thunderstorm in a small town in Karnataka, the local civic body advises people to stay inside their parked buses and cars instead of standing outside under shop awnings. Chapter 6 supports this advice mainly because
- A. Buses and cars have radios that warn passengers about the next lightning strike
- B. Awnings always attract lightning more than vehicles
- C. Sitting inside a closed bus or car is comparatively safer during lightning, while shop awnings on the street do not provide this protection
- D. Cars have lightning conductors built into their tyres
Q26. A lightning conductor on a tall building has one end pointed and kept higher than the top of the building, and the other end buried deep in the ground. Together these two design features
- A. Provide a low-resistance metallic path that captures the lightning's charges at the top and safely transfers them to the earth, protecting the building
- B. Make the building look taller and more impressive
- C. Increase the building's resistance to earthquakes by holding the structure together
- D. Reduce the electricity bill by collecting free electric current from clouds
Q27. Pre-monsoon thunderstorms in Kerala, Karnataka and Tamil Nadu that help fruit such as mangoes are commonly known as
- A. Kalboishakhi
- B. Mango showers
- C. Bordoisila
- D. Western disturbances
Q28. An IMD bulletin warns coastal families in Odisha that a severe cyclone will hit their district within 12 hours. Which of the following is the MOST appropriate immediate action?
- A. Stand near the seashore to observe how high the storm surge will rise
- B. Move with the family and an emergency kit to a designated cyclone shelter and listen to official updates
- C. Spread loose sheets of metal on the rooftop to protect it from rain
- D. Open all doors and windows of the house permanently and leave for a long picnic
Q29. Which of the following is the BEST set of items for an emergency kit recommended in Chapter 6 for families in a cyclone-prone coastal area?
- A. Festive crackers, decorative lights and bright posters
- B. Cricket bats, footballs and music speakers
- C. Drinking water, dry food, a torch, batteries, basic medicines and important documents
- D. Heavy iron tools and metal sheets to attract lightning safely
Q30. In Activity 6.5, an inflated balloon and a deflated balloon are connected through a straw with a clip in between. When the clip is opened, the air flow continues until
- A. The deflated balloon becomes completely empty
- B. The inflated balloon bursts due to extra air
- C. Both balloons reach the same size, because the air pressures inside them have become equal
- D. The straw freezes and blocks any further flow

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