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Year 9 Chemistry Revision

Total questions: 64

Worksheet time: 3hrs 44mins

Name
Class
Date
1.

Who discovered that the atom had an small, dense, positively charged center?

a)

Ernest Rutherford

b)

J.J Thomson

c)

Robert Millikan

d)

John Dalton

2.

Place the following atomic models in order, from earliest to latest:


A) Rutherford B) Thomson C) Dalton

a)

B, C, A

b)

C, A, B

c)

A, C, B

d)

C, B, A

3.

Which scientist discovered that the atom has parts - which means it can be divided?

a)

Democritus

b)

Dalton

c)

Thomson

d)

Rutherford

4.

Who discovered that atoms are mostly empty space?

a)

Dalton

b)

Thomson

c)

Rutherford

d)

Bohr

5.

Who proposed that electrons move around the nucleus in circular orbits?

a)

Dalton

b)

Thomson

c)

Rutherford

d)

Bohr

6.

Which scientist was the first person responsible for proposing the idea of atoms?

a)

Democritus

b)

John Dalton

c)

Ernest Rutherford

d)

J.J. Thomson

e)

Niels Bohr

7.

True or false: Isotopes have the same number of protons (and electrons), but a different number of neutrons.

a)

True

b)

False

8.

What does the number at the end of isotope names mean? E.g. Carbon-12, Carbon-13, Carbon-14

a)

Mass number

b)

atomic number

c)

number of protons

d)

number of neutrons

9.

Boron-10, Boron-11, and Boron-12 are all isotopes of the same element, with an atomic number of 5. How many neutrons does Boron-12 have?

a)

6

b)

7

c)

2

d)

12

10.

If fluorine has an atomic number of 9, which isotope would have 10 neutrons?

a)

Fluorine-18

b)

Fluorine-19

c)

Fluorine-20

d)

Fluorine-21

11.

A particular isotope of hydrogen has 1 proton and 3 neutrons. What will be the name of this isotope?

a)

Hydrogen-1

b)

Hydrogen-3

c)

Hydrogen-4

d)

Hydrogen-2

12.

One of the isotopes of chlorine has 17 protons and 23 neutrons. What is the name of this isotope?

(a)  

13.

An isotope of Aluminium is aluminium-25. If aluminium has an atomic number of 13, how many neutrons does this isotope have?

(a)  

14.

Which of these are isotopes of the same element? (select more than one)

a)

magnesium-23

b)

magnesium-31

c)

sodium-24

d)

magnesium-25

15.
What do these isotopes of carbon all have in common?
a)
neutrons & mass number
b)
atomic number and neutrons
c)
atomic number and electrons
d)
protons, atomic number, and mass number
16.

Which atom has 4 neutrons?

a)

Li-6

b)

Li-7

c)

Li-8

d)

they have the same # of neutrons

17.
Any atom containing an unstable nucleus is called
a)
radioisotope
b)
unisotope
c)
particles
d)
nuclei
18.
Charged particles and energy that are emitted from the nuclei of radioisotopes.
a)
nuclear radiation
b)
nuclear decay
c)
beta particles
d)
alpha particles
19.
What makes something radioactive?
a)
elements with an atomic number above 81
b)
an unstable nucleus
c)
contaminated sewage
d)
It decays over time
20.
A positively charged particle made up of two protons and two neutrons. (The same as a helium nucleus)
a)
alpha particle
b)
beta particle
c)
gamma rays
d)
charged nuclei
21.
This is an electron emitted by an unstable nucleus and has a negative charge
a)
beta particle
b)
alpha particle
c)
gamma rays
d)
nuclear electrons
22.
Is a penetrating ray of energy emitted by an unstable nucleus. 
a)
gamma ray
b)
beta particle
c)
alpha particle
23.

What is Half-life?

a)

The amount of time it takes for half the nuclei in a sample of the isotope to become radioactive

b)

The amount of time it takes for half the nucleus of the isotope to decay

c)

The amount of time it takes for half the nuclei in a sample of the isotope to decay

d)

the amount of time it takes for half the number of protons in the nucleus to decay

24.
The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?
a)
3.0g
b)
0.25mg
c)
0.3g
d)
0.25g
25.
What is the half-life of iodine-131?
a)
32 days
b)
8 days
c)
16 days
d)
24 days
26.
If one-fourth of the carbon-14 is remaining then how many half-lives have passed?
a)
1
b)
2
c)
3
d)
4
27.

Why do some elements have half-lives?

a)

they radioactively decay

b)

half of their atom gets stolen

c)

They are Twizzlers that break in half

28.
After the third half-life, how much of the sample is left?
a)
1/2
b)
1/3
c)
1/16
d)
1/8
29.

After 22,800 years, approximately what percentage of the original carbon-14 remains?

a)

15%

b)

12.5%

c)

6.25%

d)

3.125%

30.

Why do we use half life of the radioisotope carbon-14?

a)

to determine the age of fossils and ancient materials

b)

to record sea floor spreading

c)

to breakdown the process of decay

d)

to measure the radioactivity of objects

31.

Carbon dating relies on

a)

the fact that all living things contain a small amount of carbon-14

b)

organisms dying

c)

washing your hands

d)

organism remaining constant

32.

What contains carbon-14

a)

Cars

b)

Humans

c)

Trees and other plants

d)

Paper

33.

What’s the graph telling you?

a)

The graph shows an increasing trend.

b)

The graph shows a decreasing trend.

c)

The graph shows no significant change.

d)

The graph shows a cyclical pattern.

34.

Which observations prove a chemical change has occurred?

a)

Dissolving and expected color change

b)

Mixing and dissolving

c)

State of matter change and boiling water bubbles

d)

Unexpected color change and temperature change

35.

When mixing milk and vinegar, a white, chunky, solid substance is formed. What has occurred?

a)

Physical change: state of matter

b)

Chemical change: production of a solid

c)

Physical change: freezing

d)

Chemical change: rust

36.

A physical change...

a)

Changes the physical properties of an object, but does not create a new substance.

b)

Creates a new substance and cannot be undone.

37.

Is this an example of a physical or chemical change?

a)

Physical

b)

Chemical

38.

Is this an example of a physical or chemical change?

a)

Physical

b)

Chemical

39.

Is this an example of a physical or chemical change?

a)

Physical

b)

Chemical

40.

Is this an example of a physical or chemical change?

a)

Physical

b)

Chemical

41.

A change in which NEW substances are formed.

a)

Chemical change

b)

Physical change

42.
How many atoms of carbon (C) are in C6H12O6?
a)
3
b)
6
c)
12
d)
24
43.
How many atoms are there TOTAL in:
H2SO4
a)
6
b)
5
c)
7
d)
3
44.
How many elements are in C6H12O6?
a)
1
b)
2
c)
3
d)
4
45.
How many carbon atoms (C) are in a CO2 molecule?
a)
1
b)
2
c)
3
d)
0
46.
The substances at the beginning of a chemical equation are called the ____
a)
product
b)
yield
c)
chemical symbol
d)
reactants
47.
In this image, the symbols to the right of the arrow (in black) are called the_______.
a)
Products
b)
Reactants
c)
Subscripts
d)
Coefficients
48.
Na + MgF2 -->  NaF + Mg
What are the reactants?
a)
Na + MgF2
b)
Na
c)
NaF + Mg
d)
NaF
49.
Measure of the amount of matter 
a)
mass
b)
volume
c)
weight
d)
density
50.

Sodium and chlorine combine to form sodium chloride, or table salt. Sodium and chlorine are:

a)

Producers

b)

Products

c)

Reactionaries

d)

Reactants

51.

4 grams of hydrogen and 32 grams of oxygen will combine to form:

a)

36 grams of water

b)

28 grams of hydroxide

c)

32 grams of oxygen

d)

36 grams of deuterium

52.

In a chemical reaction, 4 grams of sodium must combine with how many grams of chlorine to produce 10 grams of table salt?

a)

4 grams

b)

6 grams

c)

8 grams

d)

10 grams

53.

Number placed in front of a chemical formula that tells how many molecules are present.

a)

product

b)

coefficient

c)

reactant

d)

subscript

54.

Number written below & to the right of a chemical symbol that tells how many atoms of each element

a)

subscript

b)

reactant

c)

product

d)

coefficient

55.
In chemical reactions, what does the principle of conservation of mass mean?
a)
Matter is not created or destroyed.
b)
The total mass of the reactants is greater than the total mass of the products.
c)
The total mass of the reactants is less than the total mass of the products.
d)
Matter is not changed.
56.
Is this balanced?
Al + O2 → 2Al2O3
a)
Yes
b)
No
57.
How many HCl molecules do you need to balance this equation? 
Mg +  __HCl --->  MgCl2 + H2
a)
1
b)
2
c)
3
d)
4
58.
Is the following equation balanced?
2C2H2 + 5O2 --> 4CO2 + 2H2O
a)
yes
b)
no
59.
Which of the following equations are correctly balanced?
a)
12CO2 +H2O --> C6H12O6 + O2
b)
CO2 + 9H2O --> C6H12O6 + O2
c)
CO2 + H2O --> 3C6H12O6 + O2
d)
6CO2 + 6H2O --> C6H12O6 + 6O2
60.

Balance the following equation:

___ H2+ ___ O2→___ H2O

a)

1, 1, 3

b)

2, 2, 2

c)

1, 2, 1

d)

2,1, 2

61.

Balance the following equation:

___ SeCl6+ ___ O2→___ SeO2+____Cl2

a)

1, 1, 1, 3

b)

2, 1, 2, 1

c)

1, 2, 1, 2

d)

2, 2, 2, 4

62.

Chemical Equation

a)

A representation of a chemical reaction

b)

the starting materials in a chemical reaction

c)

the new substances that are formed in a chemical reaction

d)

tells how many atoms, molecules, or formula units take part in a reaction

63.

Balance this equation

_Al +_HCl --> _H2 +_AlCl3

a)

2,6,3,2

b)

it's already balanced

c)

4,12,3,4

d)

2,1,4,5

64.

The coefficient in 3H2O is

a)

6

b)

5

c)

2

d)

3

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