M(H3PO4)=3+31+16*4=98г/моль
n(H3PO4)=m/M
n(H3PO4)=19.6/98=0.2моль
Ответ: <span>n(H3PO4)=0.2моль</span>
4P + 502 = 2P2O5
2Zn + O2 = 2Zn0
4Fe + 3O2 = 2Fe2O3
2Cu+O2=2CuO
CuO+2HNO3=Cu(NO3)2+H2O
Cu(NO3)2+2NaOH=Cu(OH)2+2NaNO3
Cu(OH)2=CuO+H2O
CuO+H2=Cu+H2O
1.1
2.2
3.2
4.3
5.3
6.3
7.А-4 Б-2 В-1 Г-5
8.3.4.5