Symbols, formulae and equations help chemists to explain chemical reactions in detail.

Which is the correct formula for sodium oxide?

Na_{2}O

NaO

NaO_{2}

Which is the correct formula for magnesium nitride?

MgN

Mg_{2}N_{3}

Mg_{3}N_{2}

Which is the correct formula for sodium hydroxide?

Na(OH)

NaOH

Na(OH)_{2}

Which is the correct formula for ammonium carbonate?

NH_{4}CO_{3}

(NH_{4})_{2}CO_{3}

NH_{4}(CO_{3})_{2}

Which is the correct sequence of numbers to get the following equation to balance? _C_{3}H_{8} + _O_{2} → _CO_{2} + _H_{2}O

1, 7, 3, 8

2, 8, 6, 8

1, 5, 3, 4

Which is the correct sequence of numbers to get the following equation to balance: _ Li + _N_{2} → _Li _{3}N

3, 1, 1

6, 1, 2

6, 1, 1

The half equation for the conversion of copper(II) ions to copper is

Cu^{2+} + 2e^{-} → Cu

2Cu^{2+} + 4e^{-} → Cu_{2}

Cu^{2+} → Cu + 2e^{-}

Chlorine reacts with sodium iodide to form sodium chloride and iodine. Which of the following is the ionic equation for this reaction?

2NaI + Cl_{2} → 2NaCl + I_{2}

2I^{-} + 2Cl → 2Cl^{-} + 2I

2I^{-} + Cl_{2} → 2Cl^{-} + I_{2}

Which of the balanced symbol equations is correct for the following word equation? calcium hydrogencarbonate + sulfuric acid → calcium sulfate + carbon dioxide + water

CaHCO_{3} + H_{2}SO_{4} → CaSO_{4} + H_{2}O + CO_{2}

Ca(HCO)_{3} + HSO_{4} → CaSO_{4} + H_{2}O + CO_{2}

Ca(HCO_{3})_{2} + H_{2}SO_{4} → CaSO_{4} + 2H_{2}O + 2CO_{2}