Unit 1

Question 1

What is matter

Answer 1

Matter is anything that takes up space

Question 2

What were the four states of matter as proposed by Aristotle?

Answer 2

Earth, fire, water, and air

Question 3

What are the four states of matter that we now accept in modern times?

Answer 3

Solid, liquid, gas, and plasma

Question 4

What are the terms used to describe changes in state?

Answer 4

Melting, freezing, sublimation, deposition, condensation, and vaporization.

Question 5

What are some characteristics of pure substances?

Answer 5

1. They are made up of same kind of atom or molecule.
2. They can be an element or compound.
3. They are homogeneous in nature.
4. They have definite chemical formula.
5. They can not be separated by physical methods.
   6.They have fixed boiling and melting points

Question 6

Pure substances can be categorized into two different groups. What are these two groups called? Define
& give an example for each one.

Answer 6

Elements : Gold:
It is homogeneous in nature made up of only one kind of atom.

Compound : Water,H2O :

It is composed of two or more elements and chemically combined in a fixed proportion

Question 7

Define solution, solute and solvent.

Answer 7

A solution is a homogeneous mixture of one or more solutes dissolved in a solvent.
solvent: the substance in which a solute dissolves to produce a homogeneous mixture.
solute: the substance that dissolves in a solvent to produce a homogeneous mixture

Question 8

What is a mechanical mixture?

Answer 8

a mixture whose components are separable by mechanical means as distinguished from a chemical compound.

Question 9

Differentiate between the terms homogenous mixture & heterogeneous mixture.

Answer 9

a homogeneous mixture is one in which different parts (such as salt and water) have been uniformly combined into a new substance (salt water), while a heterogeneous mixture has parts that remain separate.

Question 10

What is a physical change? Give an example of something that has undergone a physical change.

Answer 10

A physical change is a type of change in which the form of matter is altered but one substance is not transformed into another. An example of a physical change is crumpling a sheet or paper or breaking a pane of glass or freezing water into ice.

Question 11

List 8 physical properties

Answer 11

1. colour
2. hardness
3. malleability
4. solubility
5. electrical conductivity
6. density
7. melting point,
8. boiling point

Question 12

What is a chemical change? Give an example of something that has undergone a chemical change.

Answer 12

Chemical changes occur when a substance combines with another to form a new substance an example of this is baking soda and vinegar creating carbon dioxide

Question 13

What key pieces of evidence (list five) indicate that a chemical change has taken place.

Answer 13

Color Change.
Production of an odor.
Change of Temperature.
Evolution of a gas (formation of bubbles)
Precipitate (formation of a solid)

Question 14

Differentiate between a quantitative & qualitative observations. Give examples.

Answer 14

Quantitative is numerical
Qualitative is descriptive