$M_{5O_2} = 5.32 = 160(đvC)$
$\Rightarrow m_{5O_2} = 160.1,6605.10^{-27} = 265,68.10^{-27}(kg)$
$M_{15Cl_2} = 15.71 = 1065(đvC)$
$\Rightarrow m_{15Cl_2} = 1065.1,6605.10^{-27} = 1768,4325.10^{-27}(kg)$
$M_{7Na_2SO_4} = 7.142 = 994(đvC)$
$\Rightarrow m_{7Na_2SO_4} = 994.1,6605.10^{-27} = 1650,537.10^{-27}(kg)$