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All questions of Matter for Class 8 Exam
What happens to the boiling point of a liquid when pressure increases?- a)It increases
- b)It decreases
- c)It becomes undefined
- d)It remains the same
Correct answer is option 'A'. Can you explain this answer?
What happens to the boiling point of a liquid when pressure increases?
a)
It increases
b)
It decreases
c)
It becomes undefined
d)
It remains the same
 | Clifford Academy answered |
The boiling point of a liquid increases with an increase in pressure. This is why pressure cookers can cook food faster; they create a higher pressure environment that raises the boiling point of water.
What happens to the molecules of a liquid as it heats up?- a)They become fixed in place
- b)They gain energy and move more freely
- c)They lose all movement
- d)They condense into a solid
Correct answer is option 'B'. Can you explain this answer?
What happens to the molecules of a liquid as it heats up?
a)
They become fixed in place
b)
They gain energy and move more freely
c)
They lose all movement
d)
They condense into a solid
| | Clifford Academy answered |
As a liquid heats up, its molecules gain kinetic energy and begin to move more freely. This increased motion can eventually lead to the liquid boiling and turning into gas if enough heat is applied.
What defines a diatomic molecule?- a)A molecule made of two atoms
- b)A molecule made of three or more atoms
- c)A molecule that does not exist in nature
- d)A molecule made of a single atom
Correct answer is option 'A'. Can you explain this answer?
What defines a diatomic molecule?
a)
A molecule made of two atoms
b)
A molecule made of three or more atoms
c)
A molecule that does not exist in nature
d)
A molecule made of a single atom
| | Clifford Academy answered |
A diatomic molecule is defined as a molecule consisting of two atoms. Common examples include oxygen (O2) and hydrogen (H2). This classification is important in understanding the composition of many gases in the atmosphere.
What is matter defined as in scientific terms?- a)Anything that has weight and takes up space
- b)Only gases that can be compressed
- c)Only substances that exist in solid form
- d)Anything that can be seen with the naked eye
Correct answer is option 'A'. Can you explain this answer?
What is matter defined as in scientific terms?
a)
Anything that has weight and takes up space
b)
Only gases that can be compressed
c)
Only substances that exist in solid form
d)
Anything that can be seen with the naked eye
| | Clifford Academy answered |
Matter is defined as anything that has mass and occupies space. This includes all forms of matter—solids, liquids, and gases. Understanding this definition is fundamental in studying physical science, as it encompasses all physical substances around us.
What causes the cooling effect when sweat evaporates from the skin?- a)Sweat releases heat into the air
- b)Sweat forms a solid
- c)Sweat has a high boiling point
- d)Sweat absorbs heat from the skin
Correct answer is option 'D'. Can you explain this answer?
What causes the cooling effect when sweat evaporates from the skin?
a)
Sweat releases heat into the air
b)
Sweat forms a solid
c)
Sweat has a high boiling point
d)
Sweat absorbs heat from the skin
| | Clifford Academy answered |
When sweat evaporates, it absorbs heat from the skin, which cools the surface. This cooling effect is beneficial for regulating body temperature, especially in hot conditions.
How do molecules behave in a gas state?- a)They combine to form larger structures
- b)They slide over one another
- c)They move randomly and are far apart
- d)They are fixed in position and vibrate
Correct answer is option 'C'. Can you explain this answer?
How do molecules behave in a gas state?
a)
They combine to form larger structures
b)
They slide over one another
c)
They move randomly and are far apart
d)
They are fixed in position and vibrate
| | Clifford Academy answered |
In a gas state, molecules move randomly and are spaced far apart, allowing them to fill any container they occupy. This freedom of movement is a defining characteristic of gases, contrasting significantly with the behavior of molecules in solids and liquids.
What is the melting point of ice at standard atmospheric pressure?- a)-32°C
- b)100°C
- c)0°C
- d)32°C
Correct answer is option 'C'. Can you explain this answer?
What is the melting point of ice at standard atmospheric pressure?
a)
-32°C
b)
100°C
c)
0°C
d)
32°C
| | Clifford Academy answered |
The melting point of ice at standard atmospheric pressure is 0°C. At this temperature, ice absorbs heat without changing temperature until it fully transitions into liquid water.
Which of the following correctly describes the force of attraction between molecules in solids?- a)Strong
- b)Moderate
- c)Weak
- d)Nonexistent
Correct answer is option 'A'. Can you explain this answer?
Which of the following correctly describes the force of attraction between molecules in solids?
a)
Strong
b)
Moderate
c)
Weak
d)
Nonexistent
| | Clifford Academy answered |
The force of attraction between molecules in solids is very strong due to the close proximity of the molecules. This strong intermolecular force is what gives solids their definite shape and rigid structure, distinguishing them from liquids and gases.
What process describes the change from a solid to a liquid?- a)Condensation
- b)Freezing
- c)Sublimation
- d)Melting
Correct answer is option 'D'. Can you explain this answer?
What process describes the change from a solid to a liquid?
a)
Condensation
b)
Freezing
c)
Sublimation
d)
Melting
| | Clifford Academy answered |
The process of changing from a solid to a liquid is known as melting. This occurs when a solid is heated to its melting point, allowing its molecules to gain sufficient energy to overcome their fixed positions and move freely, thus forming a liquid.
How does the presence of humidity affect the rate of evaporation?- a)Has no effect on evaporation
- b)Causes evaporation to stop completely
- c)Increases the rate of evaporation
- d)Decreases the rate of evaporation
Correct answer is option 'D'. Can you explain this answer?
How does the presence of humidity affect the rate of evaporation?
a)
Has no effect on evaporation
b)
Causes evaporation to stop completely
c)
Increases the rate of evaporation
d)
Decreases the rate of evaporation
| | Clifford Academy answered |
The presence of humidity decreases the rate of evaporation. In humid conditions, the air is already saturated with water vapor, which makes it more difficult for additional moisture to evaporate into the air. This is why clothes take longer to dry on humid days.
Which of the following best describes the characteristics of gases?- a)No fixed shape or volume
- b)Rigid structure
- c)Fixed shape and volume
- d)Fixed volume but no fixed shape
Correct answer is option 'A'. Can you explain this answer?
Which of the following best describes the characteristics of gases?
a)
No fixed shape or volume
b)
Rigid structure
c)
Fixed shape and volume
d)
Fixed volume but no fixed shape
| | Clifford Academy answered |
Gases do not have a fixed shape or volume. They expand to fill the container they are in, which is a key characteristic that distinguishes gases from solids and liquids.
What is latent heat?- a)Heat that is lost to the environment
- b)Heat that causes a temperature change
- c)Heat absorbed or released during a change of state without a temperature change
- d)Heat that is always visible
Correct answer is option 'C'. Can you explain this answer?
What is latent heat?
a)
Heat that is lost to the environment
b)
Heat that causes a temperature change
c)
Heat absorbed or released during a change of state without a temperature change
d)
Heat that is always visible
| | Clifford Academy answered |
Latent heat refers to the heat absorbed or released by a substance during a change of state (like melting or boiling) without causing a temperature change. This concept is crucial for understanding phase transitions in matter.
What does the kinetic energy of molecules in a solid primarily enable them to do?- a)Flow like a liquid
- b)Vibrate in place
- c)Combine to form larger molecules
- d)Move freely in all directions
Correct answer is option 'B'. Can you explain this answer?
What does the kinetic energy of molecules in a solid primarily enable them to do?
a)
Flow like a liquid
b)
Vibrate in place
c)
Combine to form larger molecules
d)
Move freely in all directions
| | Clifford Academy answered |
In solids, the kinetic energy of molecules primarily allows them to vibrate in place. This limited movement is due to the strong forces of attraction that hold the molecules tightly together.
What is the process called when a gas turns back into a liquid?- a)Sublimation
- b)Condensation
- c)Melting
- d)Freezing
Correct answer is option 'B'. Can you explain this answer?
What is the process called when a gas turns back into a liquid?
a)
Sublimation
b)
Condensation
c)
Melting
d)
Freezing
| | Clifford Academy answered |
The process of a gas turning into a liquid is known as condensation. This occurs when gas molecules lose energy and come together to form a liquid, a process observed when water vapor in the air cools and forms droplets.
What changes occur when a solid turns directly into a gas?- a)Freezing
- b)Sublimation
- c)Vaporization
- d)Melting
Correct answer is option 'B'. Can you explain this answer?
What changes occur when a solid turns directly into a gas?
a)
Freezing
b)
Sublimation
c)
Vaporization
d)
Melting
| | Clifford Academy answered |
The process where a solid changes directly into a gas is called sublimation. An example of sublimation occurs with dry ice (solid carbon dioxide), which transitions to gas without becoming a liquid first.
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