C解：设Mg xmol,Fe ymol,Zn zmol反应如下：Mg+H2SO4→MgSO4+H2x
x
x (mol)Fe+H2SO4→FeSO4+H2y
y
y
(mol)Zn+H2SO4→ZnSO4+H2z
z z
(mol)注：Mg-24Fe-56Zn-65SO4离子-9624x+56y+65z=60(g)
①(24+96)x+(56+96)y+(65+96)z=252(g)
②②-①得：96x+96y+96z=192
所以：x+y+z=2(mol)氢气质量：m(H2)=2x+2y+2z=2(x+y+z)=2*2=4(g)
