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relative Atomic and relative Molecular Mass

Total questions: 15

Worksheet time: 8mins

Name
Class
Date
1.

Calculate the relative atomic mass of an element if it consists of 90% of isotope A (atomic mass 10) and 10% of isotope B (atomic mass 12).

a)

10.5

b)

11.0

c)

9.8

d)

10.2

2.

Determine the relative molecular mass of H2O.

a)

20

b)

18

c)

22

d)

16

3.

What is the average atomic mass of an element if it consists of 75% of isotope X (atomic mass 20) and 25% of isotope Y (atomic mass 22)?

a)

21

b)

20

c)

19

d)

23

4.

Calculate the molar mass of CO2.

a)

36.01 g/mol

b)

50.02 g/mol

c)

28.02 g/mol

d)

44.01 g/mol

5.

If an element has three isotopes with atomic masses 10, 11, and 12, and their abundances are 20%, 30%, and 50% respectively, what is the average atomic mass?

a)

11.3

b)

12.2

c)

10.5

d)

11.8

6.

Find the relative molecular mass of CH4.

a)

22.990

b)

18.015

c)

12.011

d)

16.043

7.

What is the molar mass of NaCl?

a)

58.44 g/mol

b)

55.84 g/mol

c)

60.44 g/mol

d)

63.44 g/mol

8.

If an element has two isotopes with atomic masses 16 and 18, and their abundances are 75% and 25% respectively, what is the average atomic mass?

a)

16.5

b)

15.5

c)

17.5

d)

16.75

9.

Calculate the relative atomic mass of an element with isotopes of atomic masses 14 and 16, and their abundances are 60% and 40% respectively.

a)

14.8

b)

14.3

c)

15.2

d)

13.5

10.

Determine the molar mass of H2SO4.

a)

72.63 g/mol

b)

36.46 g/mol

c)

98.09 g/mol

d)

58.44 g/mol

11.

What is the average atomic mass of an element if it consists of 80% of isotope P (atomic mass 30) and 20% of isotope Q (atomic mass 32)?

a)

33.5

b)

29.8

c)

31.2

d)

30.4

12.

Calculate the relative molecular mass of C6H12O6.

a)

150.24

b)

90.08

c)

200.32

d)

180.16

13.

Find the molar mass of NH3.

a)

14.03 g/mol

b)

17.04 g/mol

c)

15.99 g/mol

d)

18.02 g/mol

14.

If an element has three isotopes with atomic masses 50, 52, and 54, and their abundances are 25%, 50%, and 25% respectively, what is the average atomic mass?

a)

49

b)

54

c)

52

d)

50

15.

Calculate the relative atomic mass of an element with isotopes of atomic masses 18 and 20, and their abundances are 70% and 30% respectively.

a)

18.6

b)

16.2

c)

19.8

d)

21.4