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