What is the state when two systems reach the same temperature?
Thermal radiation
Thermal expansion
Thermal equilibrium
Thermal conduction
Which of the following is a good thermal conductor?
Copper
Cardboard
Plastic
Wood
How is heat transferred along a metal rod?
By evaporation
By radiation
By convection
By conduction
What is the definition of heat?
A form of matter
Energy transferred due to a temperature difference
A type of radiation
The mass of an object
The browning of an apple after cutting is considered:
A physical change
Melting
A change of state
A chemical reaction
How is heat transferred in fluids?
By insulation
Which of the following is a chemical change?
Melting ice
Burning wood
Breaking glass
Dissolving sugar
What indicates a chemical reaction when oil reacts with caustic soda?
Emission of light
Color change
Gas evolution
Formation of a solid
What is thermal conductivity?
The ability to reflect heat
The ability to absorb heat
The ability to transfer heat through a material
The ability to store heat
In which case is heat transferred only by radiation?
Heating air in the room with a radiator
Heating a rock by the Sun
Rubbing hands together
Heating water on a stove
Why are houses in hot areas painted white?
To store heat
To reflect heat
To absorb heat
To conduct heat
Why is the heating coil placed at the bottom of an electric kettle?
To heat water by convection
To heat water by conduction
To heat water by radiation
To reduce electricity use
How is heat transferred through ironing clothes?
When sugar is heated, it turns brown due to:
Evaporation
Condensation
Dissolving
What happens in a chemical reaction at the molecular level?
Atoms are destroyed
Atoms are rearranged
Atoms are created
Atoms remain unchanged
Which of the following is a physical change?
Turning milk into yogurt
Melting of wax
Rusting of iron
Burning of bread
When 30°C metal balls are mixed with 20°C water, why is the final temperature not 25°C?
Because the mixture has the same specific heat
Because the mixture is not stirred
Because the mixture is made of substances with different masses and specific heats
Because the mixture has the same mass
Which type of clothing is preferred in summer?
Shiny and thick
Black and heavy
Light and loose
Dark and tight
How is heat transferred from the Sun to the Earth?
By reflection
When iron is exposed to moist air, it undergoes:
Rusting
Which is NOT an indicator of a chemical reaction?
Emission of odor
Formation of a precipitate
Change in volume
Change in texture
How is heat transferred in a vacuum?
Not transferred
When hydrochloric acid is added to magnesium, it produces:
Nitrogen
Carbon dioxide
Hydrogen
Oxygen
What is thermography used for?
Measuring mass
Detecting sound
Detecting heat radiation
Measuring volume
What indicates a chemical reaction when sugar is burned?
It melts
It becomes harder
It changes color and emits smoke
It dissolves
How is heat transferred from a heater to a thermometer?
Conduction only
Convection only
Radiation only
All three methods
Why does ice melt faster on some materials?
Due to color
Due to higher thermal conductivity
Due to shape
Due to thickness
What is the scientific term for energy transferred due to temperature difference?
Light
Heat
Power
Work
What is thermal equilibrium?
When two systems have the same mass and same temperature
When two systems have the same temperature
When two systems have the same density
When two systems have the same volume
What do all hot objects emit?
Ultraviolet rays
Infrared radiation
Light only
Sound waves
What is a chemical reaction?
A change in state
A process where new substances are formed
A change in temperature
A change in shape
What is the scientific term for a change that produces new substances?
Physical change
Temporary change
Reversible change
Chemical change
What happens when two systems at different temperatures come into contact?
Heat flows from the hotter system to the colder system
Heat flows from the colder system to the hotter system
Both systems become colder
No heat flows between them
Which is a good heat insulator?
Iron
Aluminum
A physical change is characterized by:
Produces new substances
The composition of the matter changes
Accompanied by light emission
The composition of the matter does not change
What is a physical change?
Formation of new substances
A change in state or shape without altering composition
A change in chemical composition
A change in color only
Which material is a poor conductor of heat?
Silver
Why are cooking pot handles made of plastic or wood?
They are cheap
They are strong
They are good insulators
They are good conductors
What happens when an ice cube is placed in boiling water?
Heat flows from water to ice
Heat flows from ice to water
Ice gains energy from surroundings
No heat flows
Why is adding food coloring to water not a chemical reaction?
Because it changes color
Because it is irreversible
Because no new substance is formed
Because it forms a new substance
Why are cooling systems used in electronic devices?
To increase weight
To increase performance
To reduce noise
To remove excess heat
What indicates a chemical reaction between baking soda and vinegar?
Temperature decrease
Gas bubbles
What safety precaution is needed when burning magnesium?
Use water to cool it
Use a plastic container
Use a protective mask
Use bare hands
What causes sea breeze during the day?
The sea and land heat equally
The land heats faster than the sea
The land cools faster than the sea
The sea heats faster than the land
Is the expansion of water in a sealed bottle in a freezer a chemical reaction?
No, because it is reversible
No, because no new substance is formed
Yes, because it changes volume
Yes, because it changes state