Science HY term 2

Question 1

What are the three most common states of matter on Earth?

Answer 1

Solid, liquid, and gas.

Question 2

Who first proposed that matter is made of tiny, indivisible particles?

Answer 2

Democritus

Question 3

What did John Dalton propose about atoms?

Answer 3

That all matter is made of atoms, atoms are indivisible, identical in each element, and combine in fixed ratios to form compounds.

Question 4

What are the three subatomic particles of an atom?

Answer 4

Protons (positive), neutrons (neutral), and electrons (negative).

Question 5

What holds particles together in solids, liquids, and gases?

Answer 5

Forces of attraction.

Question 6

Why can gases be compressed easily?

Answer 6

Because there is a lot of space between gas particles.

Question 7

What does the kinetic theory of matter state?

Answer 7

All matter is made of moving particles, and their energy increases with heat.

Question 8

What is diffusion?

Answer 8

The movement of particles from a high concentration to a low concentration.

Question 9

In which state of matter does diffusion happen fastest?

Answer 9

Gas

Question 10

Why does diffusion not happen in solids?

Answer 10

Because the particles are held tightly in fixed positions.

Question 11

What happens to particle movement when a substance is heated?

Answer 11

The particles gain kinetic energy and move faster.

Question 12

What is latent heat?

Answer 12

The heat energy used to change the state of a substance without changing its temperature.

Question 13

What is density?

Answer 13

The mass of a substance in a given volume.

Question 14

Why does ice float on water?

Answer 14

Because ice has a lower density due to more space between its particles.

Question 15

Why do solids usually have higher density than gases?

Answer 15

Because their particles are more closely packed.

Question 16

What is viscosity?

Answer 16

How thick or resistant to flow a liquid is.

Question 17

What is compressibility?

Answer 17

The ability of a substance to be squashed into a smaller volume.

Question 18

What is heat conductivity?

Answer 18

How easily heat can move through a substance.

Question 19

What materials are good conductors of heat?

Answer 19

Metals.

Question 20

What materials are good insulators?

Answer 20

Plastics and rubber.

Question 21

What is heat capacity?

Answer 21

The amount of heat energy required to raise the temperature of a substance.

Question 22

Why do different parts of food heat at different rates?

Answer 22

Because different substances have different heat capacities.

Question 23

What is air pressure?

Answer 23

The force of air particles pushing against a surface.

Question 24

What causes water pressure when swimming underwater?

Answer 24

The weight of water particles pushing down the deeper you go.

Question 25

What is a physical property of a substance?

Answer 25

A physical property is a characteristic that can be observed or measured without changing the substance into a new one.

Question 26

What do physical properties depend on?

Answer 26

They depend on the behaviour of the particles in a substance.

Question 27

What is the melting point of a substance?

Answer 27

The temperature at which it changes from solid to liquid.

Question 28

What is the boiling point of a substance?

Answer 28

The temperature at which it changes from liquid to gas.

Question 29

What is the connection between hardness and melting point?

Answer 29

Harder substances have stronger bonds, so they have higher melting points.

Question 30

. What happens to particles when a substance is heated?

Answer 30

They gain kinetic energy, vibrate or move faster, and take up more space.

Question 31

What happens to most substances when they are heated?

Answer 31

They expand (increase in size).

Question 32

What happens when substances cool down?

Answer 32

They contract (return to original size).

Question 33

What is the kinetic theory of matter?

Answer 33

It explains that matter is made of particles which are always moving, and heat energy affects how fast they move.

Question 34

How does heating affect diffusion?

Answer 34

It makes particles move faster, so diffusion happens more quickly.

Question 35

What happens to particles when ice melts?

Answer 35

They gain energy, vibrate faster, and break free from the lattice structure.