Calculating Formula Mass

The relative formula mass (RFM) of a compound is equal to the sum of its

• Mass numbers

• Atomic numbers

• Oxidation numbers

• Valence electrons

What is the atomic mass number of magnesium?

• 2

• 4

• 12

• 24

What is the relative mass number of sodium?

• 11

• 23

• 46

• 64

What is the relative formula mass of fluorine gas, F₂?

• 19

• 38

• 9

• 18

What is the relative formula mass of NaOH?

Na= 23

O= 16

H= 1

• 20

• 39

• 40

• 45

What is the relative formula mass of CO₂?

C= 12

O= 16

• 12

• 16

• 32

• 44

The formula of a compound is M(OH)₂. Given that the relative formula mass of the compound is 98, calculate the relative mass number of of M.

• 32

• 64

• 81

• 94

What is the RFM of K₂S?

K= 39

S= 32

• 110

• 120

• 78

• 140

What is the RFM of NaCl ?

Na= 23

Cl= 35.5

• 58.5

• 57

• 60

• 62

What is the RFM of C₂H₆ ?

• 60

• 30

• 48

• 110