Vidaara.orgClass 7 · Mathematics
CodeVID-M7-WS
Heat, Light and Sound — Practice Worksheet
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- All questions are compulsory.
- Choose the correct option (A, B, C or D) for each question.
- The answer key is at the end — try the paper first!
Section A — Multiple Choice (1 mark each)
35 × 1 = 35 marks
1.
Which of the following is the correct definition of temperature?
- A.Total energy of all particles
- B.Average kinetic energy of particles
- C.The flow of energy from hot to cold
- D.The mass of an object times its speed
2.
Heat is measured in which unit?
- A.Degrees Celsius (°C)
- B.Kelvin (K)
- C.Joules (J)
- D.Meters (m)
3.
A large lake at 25°C and a small cup of tea at 85°C. Which has more heat?
- A.The cup of tea
- B.The lake
- C.Both have same heat
- D.Cannot be determined
4.
Heat flows from an object with …
- A.lower temperature to higher temperature
- B.higher temperature to lower temperature
- C.higher mass to lower mass
- D.lower mass to higher mass
5.
Two metal blocks are made of the same material. Block X has mass 500 g at 100°C. Block Y has mass 100 g at 100°C. Which statement is true?
- A.Both have same heat
- B.Block X has more heat
- C.Block Y has more heat
- D.Both have same temperature but heat cannot be compared
6.
What is the purpose of the kink in a clinical thermometer?
- A.To make it look different
- B.To prevent mercury from flowing back quickly
- C.To allow mercury to expand faster
- D.To break if overheated
7.
What is the normal human body temperature in Fahrenheit?
- A.37°F
- B.98.6°F
- C.100°F
- D.212°F
8.
Which thermometer can be used to measure the temperature of boiling water?
- A.Clinical thermometer only
- B.Laboratory thermometer only
- C.Both
- D.Neither
9.
Convert 50°C to Fahrenheit.
- A.90°F
- B.100°F
- C.122°F
- D.82°F
10.
While using a laboratory thermometer, the bulb should …
- A.touch the bottom of the container
- B.be completely immersed but not touch bottom/sides
- C.be partly above the liquid
- D.be held by hand inside the liquid
11.
Which method of heat transfer can occur in a vacuum (empty space)?
- A.Conduction only
- B.Convection only
- C.Radiation only
- D.All three
12.
When water is heated in a kettle, the water at the bottom rises to the top. This is an example of …
- A.Conduction
- B.Convection
- C.Radiation
- D.Expansion
13.
Which of the following is the best conductor of heat?
- A.Wood
- B.Plastic
- C.Copper
- D.Air
14.
Why are shiny foil blankets given to athletes after a race?
- A.To keep them cool
- B.To reflect their body heat back
- C.To absorb sweat
- D.To weigh them down
15.
Which of these is NOT an example of convection?
- A.Hot air rising from a radiator
- B.Sea breeze
- C.A metal rod getting hot at one end
- D.Boiling water
16.
Which of the following is the BEST conductor of heat?
- A.Wood
- B.Plastic
- C.Silver
- D.Air
17.
Why are frying pans usually made of metal?
- A.Metal is cheaper
- B.Metal conducts heat well
- C.Metal looks attractive
- D.Metal is lightweight
18.
Which material is commonly used as an insulator in the handles of cooking utensils?
- A.Copper
- B.Aluminum
- C.Wood
- D.Iron
19.
Why does a metal spoon feel colder than a wooden spoon at room temperature?
- A.Metal is actually colder
- B.Metal conducts heat away from your hand faster
- C.Wood stores more heat
- D.Wood is warmer than metal
20.
Which of the following is an example of a heat insulator?
- A.Copper wire
- B.Aluminum foil
- C.Woolen sweater
- D.Iron nail
21.
During the day, wind blows from the sea towards the land. This is called …
- A.Land breeze
- B.Sea breeze
- C.Monsoon wind
- D.Cyclone
22.
Which surface heats up faster under the Sun?
- A.Land
- B.Water
- C.Both heat at same rate
- D.Depends on color
23.
Land breeze occurs during the …
- A.Daytime
- B.Nighttime
- C.Both day and night
- D.Only in winter
24.
What causes sea breeze and land breeze?
- A.Rotation of Earth
- B.Unequal heating of land and water
- C.Gravitational pull of Moon
- D.Magnetic field of Earth
25.
At midnight, you are standing on a beach. The wind is likely blowing from …
- A.Sea to land
- B.Land to sea
- C.Upward from the sand
- D.No wind at all
26.
When a substance is heated, its particles …
- A.move slower and come closer
- B.move faster and move apart
- C.stop moving completely
- D.change their color
27.
Which state of matter expands the MOST when heated?
- A.Solid
- B.Liquid
- C.Gas
- D.All expand equally
28.
Gaps left between railway tracks are called …
- A.Expansion joints
- B.Welding points
- C.Track separators
- D.Safety gaps
29.
A metal lid on a glass jar is stuck. Which method will help open it?
- A.Put it in the freezer
- B.Run hot water over the lid
- C.Hit it with a hammer
- D.Leave it in the sun
30.
Water freezes at 0°C. When water turns into ice, it …
- A.expands
- B.contracts
- C.stays the same volume
- D.turns into gas
31.
What does "latent" mean in the term "latent heat"?
- A.Large
- B.Hidden
- C.Liquid
- D.Hot
32.
During melting of ice at 0°C, the temperature of the ice-water mixture …
- A.increases steadily
- B.decreases steadily
- C.remains constant
- D.first increases then decreases
33.
The latent heat of vaporization is larger than the latent heat of fusion because …
- A.liquids are heavier
- B.gases are invisible
- C.breaking all bonds (liquid→gas) needs more energy than loosening bonds (solid→liquid)
- D.boiling happens at higher temperature
34.
When water freezes into ice, it …
- A.absorbs latent heat
- B.releases latent heat
- C.neither absorbs nor releases
- D.changes temperature
35.
Why does sweating cool your body?
- A.Sweat is cold when it comes out
- B.Sweat absorbs latent heat from skin to evaporate
- C.Sweat blocks heat from entering
- D.Sweat reflects sunlight
Section B — Challenge / Olympiad (2 marks each)
35 × 2 = 70 marks
36.
Which of the following scenarios violates the concept of heat flow?
- A.Ice melts in a warm room
- B.A hot pan cools on a metal counter
- C.A cold spoon becomes colder when placed in hot soup
- D.Warm air rises from a radiator
37.
Two beakers contain equal mass of water. Beaker A is at 40°C. Beaker B is at 20°C. You add the same amount of heat to both. Which will have a higher final temperature?
- A.Beaker A
- B.Beaker B
- C.Both same
- D.Depends on room temperature
38.
A scientist says: "Two objects in contact reached the same temperature, but heat continues to flow." Is this possible?
- A.Yes, if one is larger
- B.Yes, if one is metal
- C.No, heat stops when temperatures equal
- D.Yes, if they are in vacuum
39.
Which unit is used for both heat energy and other forms of energy like work?
- A.Watt
- B.Degree
- C.Joule
- D.Kelvin
40.
A 100 g iron nail at 200°C is dropped into 1 kg of water at 25°C. The final temperature is 26°C. What can you conclude?
- A.Water gained more heat than iron lost
- B.Iron lost more heat than water gained
- C.Heat lost by iron = heat gained by water
- D.Temperature of iron did not change
41.
A clinical thermometer reads 40°C. The patient's actual temperature is 39°C. What could have caused this?
- A.The thermometer was not shaken before use
- B.The kink is broken
- C.Mercury expanded too much
- D.Room temperature was high
42.
Two thermometers — one with mercury and one with alcohol — are placed in the same water. Mercury rises to 70°C. Alcohol rises to 70°C as well. What can you conclude?
- A.Mercury thermometer is faulty
- B.Alcohol thermometer is faulty
- C.Both are accurate
- D.Water temperature is 70°C
43.
At what temperature do Celsius and Fahrenheit scales show the same number?
- A.0°
- B.32°
- C.−40°
- D.100°
44.
A laboratory thermometer has 10 divisions between 30°C and 40°C. What is the least count?
- A.0.5°C
- B.1°C
- C.0.1°C
- D.2°C
45.
Why is alcohol sometimes used instead of mercury in very cold regions?
- A.Alcohol is cheaper
- B.Alcohol freezes at −115°C, mercury freezes at −39°C
- C.Alcohol expands more
- D.Alcohol is safer to drink
46.
A metal rod is heated at one end. After some time, the other end becomes hot. Which statement correctly describes the process?
- A.Heat travels as waves
- B.Particles move from hot end to cold end
- C.Particles vibrate and pass energy to neighbors
- D.Hot air carries heat along the rod
47.
A room has a radiator near the ceiling. The room does not warm up well. Why?
- A.Radiators emit only radiation
- B.Hot air stays at ceiling and does not reach floor
- C.Conduction is poor in air
- D.The radiator is too small
48.
Which surface is best for absorbing radiant heat?
- A.Polished silver
- B.White painted
- C.Dull black
- D.Transparent glass
49.
On a cold night, a glass window feels colder than the wooden door frame even though both are at the same temperature. Why?
- A.Glass has lower temperature
- B.Wood is a better conductor
- C.Glass conducts heat away from your hand faster
- D.Wood radiates more heat
50.
In which of these situations is heat transferred primarily by radiation?
- A.Frying an egg on a pan
- B.Warm air rising from a desert
- C.Feeling heat from a campfire from 5 meters away
- D.An iron rod in a furnace
51.
A student touches a metal rod and a wooden rod that have been sitting in a freezer at −10°C. Which statement is correct?
- A.Both feel equally cold
- B.The metal rod feels colder because it conducts heat faster
- C.The wooden rod feels colder because it stores more cold
- D.Neither feels cold because the room is warm
52.
A house in a desert has thick mud walls. The mud walls keep the inside cool during the day and warm at night. Why?
- A.Mud is a conductor
- B.Mud is an insulator with high thermal mass
- C.Mud reflects all radiation
- D.Mud produces heat at night
53.
Which combination of materials would make the BEST thermos flask to keep coffee hot for 12 hours?
- A.Metal inner + metal outer + no vacuum
- B.Glass inner + glass outer + vacuum + silver coating
- C.Plastic inner + plastic outer + air layer
- D.Copper inner + copper outer + black coating
54.
Why are electrical wires that carry current covered with plastic or rubber?
- A.To make them look neat
- B.Plastic and rubber are conductors
- C.Plastic and rubber are insulators that prevent electric shock and heat loss
- D.To make them heavier
55.
In a traditional Japanese house, floors are covered with tatami mats (made of rice straw and rush grass). Why do these mats feel warm to bare feet in winter even though the room is cold?
- A.The mats generate heat
- B.The mats are good insulators and prevent heat loss from feet
- C.The mats are good conductors and bring heat from the ground
- D.The mats are at a higher temperature than the air
56.
A coastal city has a temperature of 35°C at 2 PM. An inland city at the same latitude has 42°C. Which is the most likely reason?
- A.Inland city has more pollution
- B.Sea breeze cools the coastal city
- C.Land breeze cools the coastal city
- D.Coastal city has darker soil
57.
Which statement about land breeze is TRUE?
- A.It occurs when land is warmer than sea
- B.It occurs only during full moon
- C.It occurs when sea is warmer than land
- D.It blows from sea to land
58.
A student claims: "Sea breeze is stronger in summer than in winter." Is this correct?
- A.Yes, because temperature difference is larger in summer
- B.No, sea breeze is stronger in winter
- C.Sea breeze does not occur in summer
- D.Sea breeze strength is same all year
59.
Why does land heat up faster than water? (Choose the BEST reason.)
- A.Land is darker in color
- B.Water has higher specific heat capacity and mixing currents
- C.Land is closer to the Sun
- D.Water reflects more sunlight
60.
At 6 AM on a beach, the air temperature over land is 18°C and over sea is 22°C. Which direction will the wind blow?
- A.Sea to land
- B.Land to sea
- C.Upward
- D.No wind
61.
Two rods — one made of steel and one made of brass — are exactly the same length at 20°C. They are heated to 100°C. Which rod will be longer? (Steel expands less than brass.)
- A.Steel rod
- B.Brass rod
- C.Both remain equal
- D.Depends on room temperature
62.
A concrete sidewalk has gaps every few meters. In summer, the gaps almost disappear. In winter, they become wider. Why?
- A.Concrete expands in summer, contracts in winter
- B.Concrete contracts in summer, expands in winter
- C.Gaps fill with dirt in summer
- D.The sidewalk moves due to earthquakes
63.
A metal ball has a diameter of 5.00 cm at 20°C. Its coefficient of linear expansion is 0.000019 per °C. What is its approximate diameter at 120°C?
- A.5.0095 cm
- B.5.0000 cm
- C.5.095 cm
- D.4.995 cm
64.
Why does a tightly closed glass bottle filled completely with water sometimes crack when left in a freezer?
- A.Water expands when freezing
- B.Glass contracts more than water
- C.Freezer is too cold
- D.The bottle cap shrinks
65.
A thermostat uses a bimetallic strip to turn a heater on and off. As the room cools, the strip straightens and completes an electrical circuit. Which metal is on the outside when the strip is bent in a warm room?
- A.Metal with lower expansion
- B.Metal with higher expansion
- C.Both metals expand equally
- D.Cannot be determined
66.
10 g of ice at 0°C is mixed with 100 g of water at 30°C. The final temperature is 20°C. What can you conclude?
- A.Ice did not melt completely
- B.Ice melted completely and then water warmed
- C.No heat was exchanged
- D.The experiment was done in a vacuum
67.
Why does a pressure cooker cook food faster than an open pot?
- A.Higher pressure increases latent heat of vaporization
- B.Higher pressure raises boiling point, so food cooks at higher temperature
- C.Pressure cooker has less water
- D.Pressure cooker is made of metal
68.
Which statement about latent heat is TRUE?
- A.Latent heat can be measured with a thermometer
- B.Latent heat causes temperature to rise
- C.Latent heat is absorbed or released during state changes without temperature change
- D.Latent heat only applies to water
69.
A cold drink has ice cubes floating in it. After 10 minutes, the ice cubes have melted but the drink temperature is still 0°C. Where did the heat to melt the ice come from?
- A.From the surrounding air only
- B.From the drink itself
- C.From the glass
- D.From the ice cubes themselves
70.
You have two identical burners. You put 1 kg of ice at 0°C on one and 1 kg of water at 0°C on the other. Which will reach 100°C first? (Both receive same heat per second.)
- A.The ice will reach first
- B.The water will reach first
- C.Both reach at same time
- D.Cannot be determined
Answer Key
Section A — Multiple Choice (1 mark each)
- (B) Average kinetic energy of particles
- (C) Joules (J)
- (B) The lake
- (B) higher temperature to lower temperature
- (B) Block X has more heat
- (B) To prevent mercury from flowing back quickly
- (B) 98.6°F
- (B) Laboratory thermometer only
- (C) 122°F
- (B) be completely immersed but not touch bottom/sides
- (C) Radiation only
- (B) Convection
- (C) Copper
- (B) To reflect their body heat back
- (C) A metal rod getting hot at one end
- (C) Silver
- (B) Metal conducts heat well
- (C) Wood
- (B) Metal conducts heat away from your hand faster
- (C) Woolen sweater
- (B) Sea breeze
- (A) Land
- (B) Nighttime
- (B) Unequal heating of land and water
- (B) Land to sea
- (B) move faster and move apart
- (C) Gas
- (A) Expansion joints
- (B) Run hot water over the lid
- (A) expands
- (B) Hidden
- (C) remains constant
- (C) breaking all bonds (liquid→gas) needs more energy than loosening bonds (solid→liquid)
- (B) releases latent heat
- (B) Sweat absorbs latent heat from skin to evaporate
Section B — Challenge / Olympiad (2 marks each)
- (C) A cold spoon becomes colder when placed in hot soup
- (A) Beaker A
- (C) No, heat stops when temperatures equal
- (C) Joule
- (C) Heat lost by iron = heat gained by water
- (A) The thermometer was not shaken before use
- (D) Water temperature is 70°C
- (C) −40°
- (B) 1°C
- (B) Alcohol freezes at −115°C, mercury freezes at −39°C
- (C) Particles vibrate and pass energy to neighbors
- (B) Hot air stays at ceiling and does not reach floor
- (C) Dull black
- (C) Glass conducts heat away from your hand faster
- (C) Feeling heat from a campfire from 5 meters away
- (B) The metal rod feels colder because it conducts heat faster
- (B) Mud is an insulator with high thermal mass
- (B) Glass inner + glass outer + vacuum + silver coating
- (C) Plastic and rubber are insulators that prevent electric shock and heat loss
- (B) The mats are good insulators and prevent heat loss from feet
- (B) Sea breeze cools the coastal city
- (C) It occurs when sea is warmer than land
- (A) Yes, because temperature difference is larger in summer
- (B) Water has higher specific heat capacity and mixing currents
- (B) Land to sea
- (B) Brass rod
- (A) Concrete expands in summer, contracts in winter
- (A) 5.0095 cm
- (A) Water expands when freezing
- (B) Metal with higher expansion
- (B) Ice melted completely and then water warmed
- (B) Higher pressure raises boiling point, so food cooks at higher temperature
- (C) Latent heat is absorbed or released during state changes without temperature change
- (B) From the drink itself
- (B) The water will reach first
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