Chapter 3, Problem 129CP

When ${\text{M}}_{\text{2}}{\text{S}}_{\text{3}}\text{(}s\text{)}$ is heated in air, it is converted to ${\text{MO}}_{\text{2}}\text{(}s\text{)}$ .A 4.000-g sample of
${\text{M}}_{\text{2}}{\text{S}}_{\text{3}}\text{(}s\text{)}$ shows a decrease in massof 0.277 g when it is heated in air. What is the averageatomic mass of M?