Chapter 6 Molecules And Matter

Question 1

What is density defined as?

Answer 1

Density is defined as mass per unit volume.

Question 2

What are the units for measuring density?

Answer 2

Common units include kg/m³ and g/cm³.

Question 3

What is the density of concrete compared to wood?

Answer 3

The density of concrete is about three times the density of wood.

Question 4

How is density calculated?

Answer 4

Density, p = mass (m) / volume (V).

Question 5

If an object has a density lower than that of water, what will happen?

Answer 5

It will float in water.

Question 6

Fill in the blank: 1 kg = _______ g.

Answer 6

1000 g.

Question 7

Fill in the blank: 1 m³ = _______ cm³.

Answer 7

1000000 cm³.

Question 8

What is standard form used for?

Answer 8

It is useful for working with very large numbers and converting values to SI units.

Question 9

In standard form, how is a number expressed?

Answer 9

A × 10^n, where A is between 1 and 10.

Question 10

How do you rearrange the density equation to find mass?

Answer 10

m = p × V.

Question 11

What should be done before measuring the mass of an object on an electronic balance?

Answer 11

Ensure the balance reads zero.

Question 12

How do you calculate the volume of a regular solid?

Answer 12

Use the formula: volume = length × width × height.

Question 13

How can you calculate the volume of an object submerged in a liquid?

Answer 13

By observing the change in water level in a measuring cylinder after submerging the object.

Question 14

What is the first step to measure the density of a liquid?

Answer 14

Measure the mass of an empty beaker using a balance.

Question 15

What is the formula to calculate the mass of the liquid?

Answer 15

Total mass of beaker and liquid - mass of empty beaker.

Question 16

What is the formula for calculating density?

Answer 16

Density = mass / volume.

Question 17

What is the safety precaution mentioned for density tests?

Answer 17

Take care not to spill any liquids and inform your teacher if you do.

Question 18

What should you consider when choosing an instrument for measurement?

Answer 18

The resolution and range of the instrument.

Question 19

True or False: Objects with a lower density than water will float.

Answer 19

True.

Question 20

Fill in the blank: The formula for density is ______.

Answer 20

density = mass / volume.

Question 21

What is the relationship between density and floating in water?

Answer 21

Objects with a density less than 1000 kg/m³ will float.

Question 22

What is the kinetic theory of matter?

Answer 22

The theory that explains the behavior of solids, liquids, and gases based on the movement and arrangement of particles.

Question 23

What are the three states of matter?

Answer 23

Solid, liquid, gas.

Question 24

How do the particles in a solid behave?

Answer 24

The particles are held tightly to each other in fixed positions.

Question 25

How do the particles in a liquid behave?

Answer 25

The particles move about at random and are in contact with each other, being more energetic than particles in a solid.

Question 26

How do the particles in a gas behave?

Answer 26

The particles move about randomly and are far apart, making gases much less dense than solids and liquids.

Question 27

What happens to the mass of a substance during a change of state?

Answer 27

The mass stays the same because the number of particles stays the same.

Question 28

Fill in the blank: The mass of the substance after a change of state is the same as the mass of the substance _______.

Answer 28

before.

Question 29

True or False: The movement of particles in a solid is random.

Answer 29

False.

Question 30

What is a key point about gases compared to solids and liquids?

Answer 30

Gases are the most energetic of the states of matter.

Question 31

Describe the energy levels of particles in solids, liquids, and gases.

Answer 31

Particles in solids have low energy, particles in liquids have moderate energy, and particles in gases have high energy.

Question 32

What safety precaution should be taken when dealing with boiling water?

Answer 32

Take care to avoid burns or scalds.

Question 33

What occurs when water is heated before it boils?

Answer 33

The water gradually turns into steam.

Question 34

What happens to water when it is put into a freezer?

Answer 34

It gradually turns to ice.

Question 35

What are the three states of matter?

Answer 35

Solid, Liquid, Gas ## Footnote These states are distinguished by their physical properties and behaviors.

Question 36

What is the process of changing from a liquid to a gas called?

Answer 36

Vaporisation or boiling ## Footnote This process requires heat energy to overcome intermolecular forces.

Question 37

What is the term for the change from gas to liquid?

Answer 37

Condensation ## Footnote This occurs when gas loses heat energy.

Question 38

What is the process of changing from solid to liquid?

Answer 38

Melting ## Footnote This requires heat energy to break the bonds holding the solid structure.

Question 39

What is the term for the change from liquid to solid?

Answer 39

Solidifying or freezing ## Footnote This occurs when a liquid loses heat energy.

Question 40

What happens to matter during a change of state?

Answer 40

It undergoes a physical transformation. ## Footnote This transformation involves changes in temperature and energy.

Question 41

Fill in the blank: The change of state is the same for all substances, regardless of their _____ .

Answer 41

composition ## Footnote The principles of change of state apply universally.

Question 42

What is the temperature at which a solid turns to a liquid called?

Answer 42

Melting point

Question 43

What is the temperature at which a liquid turns to a gas called?

Answer 43

Boiling point

Question 44

True or False: The temperature stays constant at 100°C while water turns to steam.

Answer 44

True

Question 45

What happens to the temperature of ice when it is heated steadily below 0°C?

Answer 45

It increases until it reaches 0°C

Question 46

Describe the process that occurs when water in a beaker reaches 100°C.

Answer 46

The temperature stays constant while the water turns to steam

Question 47

Fill in the blank: Evaporation happens at any temperature - _______ happens only at the boiling point.

Answer 47

Boiling

Question 48

What is the difference between evaporation and boiling?

Answer 48

Boiling occurs throughout a liquid at its boiling point; evaporation occurs from the surface when below boiling point.

Question 49

What is the effect of salt on the freezing point of water?

Answer 49

Salt water has a lower freezing point than pure water

Question 50

What is the purpose of scattering a mixture of salt and grit on icy roads?

Answer 50

To lower the freezing point and improve traction

Question 51

For a pure substance, what is the relationship between melting point and solidification?

Answer 51

The melting point is the same temperature at which it solidifies

Question 52

What is required to melt a solid or to boil a liquid?

Answer 52

Energy

Question 53

What does the flat section of a temperature-time graph represent?

Answer 53

The melting point or the boiling point of a substance

Question 54

How does the temperature of a substance change when it is at its melting point?

Answer 54

It remains constant until the entire substance has melted

Question 55

True or False: Evaporation occurs when the temperature is at or above the boiling point.

Answer 55

False

Question 56

What happens to the particles of a substance as it reaches its melting point?

Answer 56

They change from a solid state to a liquid state

Question 57

What is the formula for latent heat?

Answer 57

E=lm or Energy(joules)=latent heat capacity(j/kg) x mass(kg)

Question 58

What is latent heat?

Answer 58

The energy needed for a substance to change state without changing its temperature

Question 59

What is the specific latent heat of fusion?

Answer 59

The energy needs to change the state of 1kg of the substance from solid to liquid, at its melting point

Question 60

What is the specific latent heat of vaporization?

Answer 60

The energy needs to change the state of 1kg of the substance from liquid to vapour, at its boiling point

Question 61

What is pressure caused by?

Answer 61

The random impact of gas particles on surfaces that are in contact with the gas.

Question 62

When does pressure increase?

Answer 62

Pressure increases as temperature increases. Molecules of gas collide repeatedly with each other, each impact exerts a tiny force. The pressure of a gas on a surface is the total force exerted on a unit area of the surface

Question 63

What does increasing the temperature of a sealed container do?

Answer 63

Increases the gas pressure. Energy transfer increases kinetic energy of molecules, avg kinetic energy of molecules increases. The avg speed of the molecules increases when Kinetic energy increases. So molecules hit surface more increasing pressure

Question 64

What is Brownian motion?

Answer 64

The unpredictable motion of smoke particles, colliding at random. Evidence of random motion in gas molecules