Answer
a. formula mass for N$O_{2}$ is 46 amu.
b. formula mass for glucose $C_{6}$$H_{12}$$O_{6}$ is 180 amu.
c. FM of NaOH is 40 amu
d. FM of Mg$(OH)_{2}$ = 58 amu
Work Step by Step
a. formula mass for N$O_{2}$.
FM of N$O_{2}$ is the sum of atomic masses of all atoms in formula:
1 x AM of N = 14.0 amu
2 x AM of O = 2 x 16.0 = 32.0 amu
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FM = 14.0 amu + 32.0 amu = 46.0 amu
FM of N$O_{2}$ is 46 amu.
b. formula mass for glucose $C_{6}$$H_{12}$$O_{6}$.
FM of $C_{6}$$H_{12}$$O_{6}$ is the sum of atomic masses of all atoms in formula:
6 x AM of C = 6 x 12.0 amu = 72.0 amu
12 x AM of H= 12 x 1.0 amu = 12.0 amu
6 x AM of O = 6 x 16.0 amu = 96.0 amu
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FM of $C_{6}$$H_{12}$$O_{6}$ = 72.0 amu + 12.0 amu + 96.0 amu
FM of $C_{6}$$H_{12}$$O_{6}$ = 180.0 amu
FM of $C_{6}$$H_{12}$$O_{6}$ = 180 amu.
c. formula mass for sodium hydroxide NaOH.
1 x AM of Na = 1 x 23.0 amu = 23.0 amu
1 x AM of O = 1 x 16.0 amu =16.0 amu
1 X AM of H = 1 x 1.0 amu = 1.0 amu
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FM of NaOH = 23.0 amu + 16.o amu + 1.0 amu
FM of NaOH is 40 amu
d. Formula mass Mg$(OH)_{2}$
1 x AM of Mg = 1 x 24.3 amu = 24.3 amu
2 X AM of O= 2 x 16.0 amu = 32.0 amu
2 x AM of H = 2 x 1.0 amu = 2 amu
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FM of Mg$(OH)_{2}$ = 24.3 amu + 32.0 amu + 2.0 amu
FM of Mg$(OH)_{2}$ = 58.3 amu
FM of Mg$(OH)_{2}$ = 58 amu