A.5
B.10
C.12
D.6

A.Mg.
B.Ba.
C.Na.
D.K.

A.NaOH.
B.MgCl2.
C.Na3PO4.
D.Ca(OH)2.

A.FeCl2.
B.FeO.
C.FeCl3.
D.Fe3O4.

A.HCl.
B.AgNO3.
C.H2O.
D.KOH.

A.C17H35COONa.
B.C17H33COONa.
C.C6H5COONa.
D.C15H31COONa.

A.Na2CO3.
B.NaHCO3.
C.NaOH.
D.Na2SO4.

A.Toluen.
B.Stiren.
C.Axetilen.
D.Xilen.

A.47,2.
B.46,4.
C.54,2.
D.48,2.

A.Not until it started to rain heavily did the boy got out of his house.
B.No sooner had the boy got out of his house than it started to rain heavily.
C.Hardly had it started to rain heavily when the boy got out of his house.
D.It had rained heavily before the boy got out of his house.