(a) ____Fe(s) + ____S(s)h____Fe2S3(s)

(b) ____P4
(s) + ____H2(g)h____PH3(g)
(c) ____NO(g) + ____Cl2(g)h____NOCl(g)
(d) ____SiCl4(l ) + ____Mg(s)h____Si(s) +
____MgCl2(s)

what is the question here?