• 62 questions

Polyatomic Ion Quiz

Tap the right formula or name and see the ion and its acid.

What is the formula of the sulfite ion?

Pick an answer, then press Check answer. Then you see Correct or Not quite, with the reason. Keys: A to D pick, Enter checks.

Print covers the next 25 questions. Share this set copies a link to the same questions in the same order.

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Unofficial practice questions, not affiliated with any school, exam board or textbook publisher. Bank checked September 23, 2026.

Next step Next: which compounds of these ions dissolve

All 62 questions

Name to formula 25

  • What is the formula of the acetate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the ammonium ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the azide ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the bicarbonate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the carbonate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the chlorate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the chlorite ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the chromate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the cyanide ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the dichromate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the dihydrogen phosphate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
Show all 62 questions (51 more)

Name to formula, continued

  • What is the formula of the hydrogen phosphate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the hydrogen sulfate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the hydrogen sulfite ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the hydronium ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the hydroxide ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the hypochlorite ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the nitrate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the nitrite ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the perchlorate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the permanganate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the peroxide ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the phosphate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the sulfate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is the formula of the sulfite ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.

Formula to name 25

  • Which ion is CH₃COO⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is ClO⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is ClO₂⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is ClO₃⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is ClO₄⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is CN⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is CO₃²⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is CrO₄²⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is Cr₂O₇²⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is HCO₃⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is HPO₄²⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is HSO₃⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is HSO₄⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is H₂PO₄⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is H₃O⁺? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is MnO₄⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is NH₄⁺? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is NO₂⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is NO₃⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is N₃⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is OH⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is O₂²⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is PO₄³⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is SO₃²⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which ion is SO₄²⁻? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.

Patterns and acids 12

  • Acetate is written CH₃COO⁻ in the table. Which other formula is the same ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • An -ate ion gives an acid ending in what? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • An -ite ion gives an acid ending in what? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Bicarbonate is carbonate with what added? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Compared with an -ate ion, an -ite ion of the same element has what? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Nitrate is NO₃⁻. Does every -ate ion have three oxygen atoms? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What does the prefix hypo- mean in hypochlorite? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What does the prefix per- mean in perchlorate? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • What is an oxyanion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which acid is related to the sulfate ion? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which list runs from the most oxygen atoms to the fewest? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.
  • Which two ions in the common list carry a positive charge? OpenStax Chemistry 2e, section 2.6, Table 2.5. Read 2026-09-23.

How this list was compiled: Questions, wrong choices and explanations were written for this site. The 25 ions, their formulas, charges and related acids are the list in OpenStax Chemistry 2e, section 2.6, Table 2.5 (https://openstax.org/books/chemistry-2e/pages/2-6-ionic-and-molecular-compounds), and the -ate, -ite, per- and hypo- pattern is from the same section. Read 2026-09-23. Licence: own work

How it works

This polyatomic ion quiz drills the 25 common ions a chemistry course asks you to memorize: name to formula, formula to name, and the naming pattern. Every answer shows the charge and the related acid.

Read the full guide

Three sets

Name to formula asks for sulfate, nitrite or dichromate; the wrong choices have the right atoms and the wrong charge, or a close cousin. Formula to name runs the other way. Patterns and acids covers -ate and -ite, per- and hypo-, and -ic and -ous acids.

Memorizing polyatomic ions

Learn one family at a time: the four chlorine oxyanions, the three phosphates, the sulfates and sulfites. Missed questions come back until you get them right, and Print gives a paper test.

  • Learn the -ate ion of each family; the -ite ion has one oxygen less and the same charge.
  • Adding H to an ion lowers the charge by one: CO₃²⁻ becomes HCO₃⁻, PO₄³⁻ becomes HPO₄²⁻.

Questions and answers

Which polyatomic ions should I memorize?

The 25 in this quiz are the list in OpenStax Chemistry 2e, Table 2.5, which the book says to memorize: ammonium and hydronium, hydroxide and peroxide, the carbon, nitrogen, sulfur, phosphorus and chlorine oxyanions, cyanide, azide, chromate, dichromate and permanganate.

Which polyatomic ions are positive?

Of the common ones, only ammonium, NH₄⁺, and hydronium, H₃O⁺. Every other ion in the list is negative.

Is this enough for AP Chemistry?

It covers the common ions an AP or first-year college course uses. Your teacher's list may add a few, such as thiosulfate or oxalate, which are not in this set.

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