Answer is: sulfur, arsenic, selenium, silicon and antimony.
1) Sulfur (S) can form, for example, sulfuric acid (H₂SO₄) or acidic oxide, sulfur(VI) oxide (SO₃).
2) Arsenic (As) can form arsenous acid (H₃AsO₃).
3) Selenium (Se) can form selenic acid (H₂SeO₄).
4) Silicon (Si) can form orthosilicic acid Si(OH)₄ and metasilicic acid SiO(OH)₂.
5) Antimony (Sb) can form antimonic acid, as the hydrate HSb(OH)₆.
