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Chemistry Counting Atoms

Total questions: 20

Worksheet time: 10mins

Name
Class
Date
1.

A subscript is the small number below a(n) ________ that tells the number of _______ of that element.

a)

element symbol; atoms

b)

atom; element symbol

c)

subscript; protons

d)

compound; elements

2.

If there is no subscript, there is ______ atom(s) of that element

a)

0

b)

1

c)

2

d)

10

3.

How many atoms are in the element Carbon in this compound?

H2C3O4N5

a)

2

b)

4

c)

5

d)

3

4.

How many TOTAL atoms are in this compound?

H2C3O4N5

a)

14

b)

15

c)

5

d)

19

5.

Which of these is NOT a compound?

a)

OH

b)

H2Cr

c)

PNi

d)

Cr3

6.

Element or compound?

O2

a)

Compound

b)

Element

7.

Which is the correct formula for:

three hydrogen (H)

one sulfur (S)

four oxygen (O)

a)

H3SO4

b)

HSO4

c)

H4S3O

d)

H2O

8.

The substances at the beginning of a chemical equation are called the ____

a)

product

b)

yield

c)

reactants

d)

chemical symbol

9.

What is a chemical equation?

a)

A short way to show a chemical reaction using symbols

b)

A way to explain a chemical reaction using words

10.

Name ALL the evidences that show a chemical reaction has occurred.

a)

light, precipitate, odor,

b)

temperature, smell, light, conductivity, taste

c)

color, gas, light

d)

color, gas, light, temperature, precipitate

11.

How many atoms are there in total? 5 Ca(OH)2

a)

5

b)

10

c)

25

d)

15

12.

3Cr(MnO4)6 - how many Cr?

a)

1

b)

18

c)

9

d)

3

13.

How many elements are in this equation: NaCl

a)

1

b)

4

c)

3

d)

2

14.

How many total atoms are in H20

a)

1

b)

3

c)

2

d)

4

15.

How many molecules are in 2Mg(SO3)2

a)

0

b)

2

c)

1

d)

3

16.

what is the five in this equation 5Cu(NO3)2

a)

Coefficient

b)

Subscript

c)

Atom

17.

Which of the following is a compound?

a)

C

b)

Co

c)

CO2

d)

O2

18.

The blue numbers in the image below represent

a)

none of the answers are correct

b)

coefficients

c)

Subscripts

19.

In the equation, 2Mg + O2 ---> 2MgO, which are the reactants?

a)

Mg and O

b)

MgO

c)

Mg and MgO

d)

O and MgO

20.

5CO2

How many molecules are there? How many elements?

a)

2 elements, 5 molecules

b)

15 elements, 2 molecules

c)

5 molecules, 2 elements

d)

10 atoms, 5 elements