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3. A metal spoon is left in a bowl of hot soup.
After a few minutes, the handle becomes
hot even though it isn't touching the soup.
Which statement correctly identifies the
phenomenon? (Pattern Recognition)
(a) Heat is transferred through the
spoon by the movement of fluid
particles (convection).
Which student is correct, and what principle
(b) Heat is transferred through the of convection explains the smoke's direction?
spoon from the hot end to the (Abstract Thinking)
cooler handle by conduction, as
the spoon is a solid. (a) Farida, smoke moves downward
due to conduction, as heat travels
(c) The handle becomes hot
because it absorbs heat from the along the length of the stick.
surrounding air through radiation. (b) Rohan, smoke rises upward due to
convection, because the hot smoke
(d) Particles of the hot soup move into
the spoon handle, causing it to is less dense than the surrounding
air and moves upward.
become hot.
(c) Both are partially right, smoke first
4. In Ladakh, water is sprayed into freezing air
during winter to form ice stupas which melt goes down then curves up.
slowly in spring. Why does this method ensure (d) No one is correct as smoke
a water supply later? (Abstract Thinking) spreads equally in all directions
(a) Stupa's ice melts quickly due from a downward stick.
to conduction of heat from the 6. Two identical test tubes are filled with equal
ground. amounts of water. Both are heated from below
(b) Conical shape of ice stupa by a candle. In Fig. (a), the thermometer bulb
reduces heat gain, so melting is near the bottom of the water. In Fig. (b),
slows despite radiation. the thermometer bulb is near the top of the
water. After two minutes, both thermometers
(c) Freezing and melting of ice occur are read.
due to convection in air. Thermometer
Thermometer Water
(d) Stupa's ice stores water and melts
slowly by absorbing heat from the
surrounding. Water
5. A burning incense stick is fixed so it points
straight downward — the burning tip is at
the bottom. Farida predicts: 'Smoke will
travel downward because the stick points Burning
down.' Rohan predicts: 'Smoke will rise candle
upward regardless of stick orientation.' The Fig. (b)
experiment is carried out. Fig. (a)
Heat Transfer in Nature 75
