Answer
a) Pb: $86.60\%$ S: $13.40\%$
b) C: $81.71\%$ H: $8.29\%$
c) C: $79.96\%$ H: $9.39\%$ O: $10.65\%$
Work Step by Step
Atomic weights (g/mol): $Pb: 207.2,\ S:32.06,\ C: 12.011,\ H: 1.008,\ O: 15.999$
Molar masses (g/mol): $PbS: 239.27,\ C_3H_8:44.10,\ C_{10}H_{14}O: 150.22$
a) Pb: $207.2/239.27\times100\%=86.60\%$
S: $32.06/239.27\times100\%=13.40\%$
b) C: $3\times12.011/44.10\times100\%=81.71\%$
H: $8\times1.008/44.10\times100\%=18.29\%$
c) C: $10\times12.011/150.22\times100\%=79.96\%$
H: $14\times1.008/150.22\times100\%=9.39\%$
O: $15.999/150.22\times100\%=10.65\%$
