英文化学字谜6.Element found in white jewelry and also used when a

英文化学字谜
6.Element found in white jewelry and also used when a wire must be sealed in a glass tube as it expands and contracts at about the same rate as glass.（8个字母）
7.Element used as a dye and as a tincture solution in medicine.（6个字母）
9.Element used in electroplating and also in coins of small denominations.（6个字母）
6是铂，7是碘，9是什么啊