[tex]\Large\boxed{\begin{array}{l}\sf Vamos\,chamar\,este\,\acute atomo\,de\, X.\\\sf a\,massa\,do\,\acute atomo\,X\,\acute e\,dada\\\sf somando\,pr\acute otons\,com\,n\hat eutrons.\\\sf m=p+n\\\sf m=25+33\\\sf m=58.\\\sf portanto\,o\,\acute atomo\,X^{58}\,\acute e\,is\acute obaro\,do\,Cs^{58}\\\huge\boxed{\boxed{\boxed{\boxed{\sf\maltese~alternativa~a}}}}\end{array}}[/tex]
