100-15=85% pur
Zn + 2HCl => ZnCl2 + H2
65g Zn................................1 mol H2
xg Zn...................................0,02 moli H2
x=65*0,02=1,3g Zn pur (p=85%)
n=m/M=1,3/65=0,02 moli Zn pur
p=mp/mimp*100=>mimp=mp*100/p=1,3*100/85=1,53g Zn impur (15% impuritati)
R: a),b),c)