## Chemistry and Chemical Reactivity (9th Edition)

$x=0.15$
Molar mass of the compound: Cu: $15.69\%$, $63.546\ g/mol$ $15.69/100=63.546/M$ $M=405\ g/mol$ For Ba: $5.085\%$, $137.327\ g/mol$ $5.085/100=x\times137.327/405$ $x=0.15$