1.28.6% (10/35)*100%
2.880 g 100*98%=(x+100)*10%
3.2 211 mL 5000*20%=1.19*38%x
4.55 g,495 g 氢氧化钠500*1.1*10% 水500*1.1-500*1.1*10%
5.19.6% Zn+H2SO4=ZnSO4+H2
65 98
13 x
65:98=13:x x=19.6g 19.6/100=19.6%
6.11.5 g,5.8 L
7.67.5 81 t
8.(1)0.05% (2)2 000 mL