Question

Find out some more elements which have variable valency

Answer 1

Copper Cu1, 2Cu1+
Cu2+Copper [I] or Cuprous
Copper [II] or Cupric
Silver Ag1, 2Ag1+
Ag2+Silver [I] or Argentous
Silver [II] or Argentic
Mercury Hg1, 2Hg1+
Hg2+Mercury [I] or Mercurous
Mercury [II] or Mercuric
Iron Fe2, 3Fe2+
Fe3+Iron [II] or Ferrous
Iron [III] or Ferric
Tin Sn2, 4Sn2+
Ag4+Tin [II] or Stannous
Tin [IV] or Stannic
Lead Pb2, 4Pb2+
Pb4+Lead [II] or Plumbous
Lead [IV] or Plumbic
Phosphorus P3, 5 
 Sulfur S4, 6

Answer 2

Iron Fe
Tin Sn
Manganese Mn
Copper Cu