Ответ:

1)Дано

m(Pb)=72.45 ;

m(PbO)-?

2Pb+O2=2PbO

n(Pb)=m/M

n(Pb)==72.45/207=0.35 моль

m(PbO)=n×Mr=0.35×223=78.05 г

2)Дано

N(HF)=2.4088×10^23

m(HF)-?

V(HF)-?

m((HF)=(Mr×N)/N(A)

m(HF)=(20×2.4088×10^23)/6.02×10^23=6.71 г

V(HF)=(Vm×N)/N(A)=(22.4×2.4088)/6.02×10^23=8.96 л