Chemistry 0620 · IGCSE · The mole and the Avogadro constant

The mole and the Avogadro constant — practice question

Steam reacts with magnesium. $\text{Mg} + \text{H}_2\text{O} \rightarrow \text{MgO} + \text{H}_2$ If $2.43\,\text{g}$ of magnesium is allowed to react with an excess of steam, $4.03\,\text{g}$ of magnesium oxide and $0.20\,\text{g}$ of hydrogen are obtained. What is formed when $7.29\,\text{g}$ of magnesium reacts with an excess of steam?

  • A$1.34\,\text{g}$ of magnesium oxide and $0.07\,\text{g}$ of hydrogen
  • B$4.03\,\text{g}$ of magnesium oxide and $0.20\,\text{g}$ of hydrogen
  • C$8.06\,\text{g}$ of magnesium oxide and $0.40\,\text{g}$ of hydrogen
  • D$12.09\,\text{g}$ of magnesium oxide and $0.60\,\text{g}$ of hydrogen

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