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Counting Atoms and Calculating Formula Mass Practice

Total questions: 30

Worksheet time: 24mins

Name
Class
Date
1.

What does the subscript represent?

a)

The number of atoms in a molecule

b)

The number of molecules

2.

The blue numbers in the image below represent ________

a)

element symbol

b)

coefficients

c)

subscripts

d)

yield

3.

The red numbers in the image below represent ________

a)

symbol

b)

coefficients

c)

subscripts

d)

equation

4.

How many Aluminum (Al) atoms are in Al2O3?

a)
3
b)
2
c)
5
5.

How many Sodium (Na) atoms are in 6 NaCl?

a)
1
b)
12
c)
6
6.

How many Hydrogen (H) atoms are in 4 H2O?

a)
6
b)
8
c)
2
d)
4
7.

How many Magnesium (Mg) atoms are in 10 MgCl2?

a)
10
b)
5
c)
20
8.

How many Oxygen (O) atoms are in 5 O2?

a)

5

b)

10

c)

2

d)

4

9.

How many Chlorine (Cl) atoms are in 7 Cl2?

a)

7

b)

14

c)

2

10.

How many hydrogen (H) atoms are in (NH4)3PO4?

a)
1
b)
4
c)
3
d)
12
11.

How many atoms of Oxygen (O) are in Fe(NO3)3 ?

a)
6
b)
3
c)
9
d)
1
12.
Which is the correct formula for:
 three hydrogen (H)
one sulfur (S)
four oxygen (O)
a)
H3SO4
b)
HSO4
c)
H4S3O
d)
H2O
13.

Which is the correct formula for:
 two hydrogen (H)
one oxygen (O)

a)

H2O

b)

HO2

c)

H2O2

d)

HO

14.

How many carbon in 2Na₂CO₃?

a)
1
b)
2
c)
3
d)
5
15.

Number of nitrogen in (NH₄)₂CrO₄?

a)
1
b)
2
c)
8
d)
16
16.

4 Fe(SO4)2

a)

Fe = 4, S= 4, O= 32

b)

Fe = 1, S = 8, O = 8

c)

Fe= 4, S = 8, S= 32

d)

Fe= 1, S= 4, O = 8

17.

4CF2Cl2

a)

C = 4, F = 4, Cl = 2

b)

C = 1, F = 8, Cl = 8

c)

C = 4, F = 8, Cl = 8

d)

C = 1, F = 4, Cl = 8

18.

A subscript behind a set of parentheses belongs to

a)

the element right before it

b)

all the elements within the parentheses before it

c)

all the elements in the parenthese after it

d)

the element right after it

19.

If there is no subscript, how many atoms of that element are there?

a)

1

b)

2

c)

3

d)

0

20.

How many K are in 5 K2(SO4)3

a)

7

b)

10

c)

30

d)

3

21.

How many S are in5 K2(SO4)3

a)

3

b)

8

c)

15

d)

5

22.
(NH4)2SO4
a)
132.1
b)
114.1
c)
132
d)
70.1
23.
Pr(OH)3
a)
191.9
b)
157.1
c)
160.9
d)
191
24.
Cs2SO4
a)
361.9
b)
361.8
c)
313.9
d)
180
25.
copper (II) nitrate
a)
187.6
b)
125.6
c)
188
d)
173.5
26.
magnesium nitride
a)
100.9
b)
101
c)
38.3
d)
116.9
27.

AlN3O9

a)

213

b)

89

c)

41

d)

150.9

28.

What is the mass of LiCl2

a)

20

b)

37

c)

42.5

d)

78

29.
NaCl
a)
58.5
b)
23
c)
35.5
d)
67.6
30.
K2S
a)
110.3
b)
110
c)
78.2
d)
110.2