Resposta :
[tex]\boxed{\begin{array}{l}\underline{\rm Transformac_{\!\!,}\tilde ao~isot\acute ermica}\\\sf P\cdot V=P_0\cdot V_0\\\sf P\cdot 40=4\cdot30\\\sf P=\dfrac{\backslash\!\!\!4\cdot3\diagup\!\!\!0}{\backslash\!\!\!4\diagup\!\!\!0}\\\sf P=3~atm\\\huge\boxed{\boxed{\boxed{\boxed{\sf\maltese~alternativa~ a}}}}\end{array}}[/tex]