Answer:45.27 Explanation: To find the mass percent of oxygen we begin by finding the mass of the molecule
N
a
2
C
O
3
N
a
=
2
⋅
22.99
=
45.98
C
=
1
⋅
12.01
=
12.01
O
=
3
⋅
15.99
=
47.97
N
a
2
C
O
3
=
105.96
Now divide the mass of Oxygen by the total mass of the molecule.
47.97
105.96
=
.4527
Multiply 100 to convert the decimal to a percent.
.4527
⋅
100
=
45.27
%