Formulae and Equations questions

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Formulae and Equations question collection

Review Formulae and Equations questions for Chemistry, with correct answers shown and coverage across chemical reactions as a rearrangement of atoms; writing formulae for simple compounds; word equations for common reactions.

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Question 1

Which is the balanced equation for forming water?
  1. \(2\mathrm{H}_{2} + \mathrm{O}_{2} \to 2\mathrm{H}_{2}\mathrm{O}\)
  2. \(\mathrm{H}_{2} + \mathrm{O}_{2} \to \mathrm{H}_{2}\mathrm{O}\)
  3. \(\mathrm{H}_{2} + \mathrm{O}_{2} \to 2\mathrm{H}_{2}\mathrm{O}\)
  4. \(2\mathrm{H}_{2} + 2\mathrm{O}_{2} \to 2\mathrm{H}_{2}\mathrm{O}\)

Question 2

How many oxygen atoms are in one formula unit of CaCO3?
  1. 3
  2. 1
  3. 2
  4. 4

Question 3

How many hydrogen atoms are in one molecule of H2SO4?
  1. 2
  2. 1
  3. 4
  4. 6

Question 4

How many atoms are in one H2SO4 molecule?
  1. 7
  2. 4
  3. 6
  4. 8

Question 5

Which formula has two hydrogen atoms for every oxygen atom?
  1. H2O
  2. HO2
  3. H2O2
  4. H3O

Question 6

If \(5\,\mathrm{g}\) of A reacts with \(7\,\mathrm{g}\) of B and all reactants are used, what mass of product forms?
  1. \(12\,\mathrm{g}\)
  2. \(2\,\mathrm{g}\)
  3. \(7\,\mathrm{g}\)
  4. \(35\,\mathrm{g}\)

Question 7

Carbon burns in oxygen to form carbon dioxide. If \(12\,\mathrm{g}\) of carbon forms \(44\,\mathrm{g}\) of CO2, what mass of oxygen reacted?
  1. \(32\,\mathrm{g}\)
  2. \(12\,\mathrm{g}\)
  3. \(44\,\mathrm{g}\)
  4. \(56\,\mathrm{g}\)

Question 8

In 2Mg + O2 → 2MgO, what does the 2 before Mg show?
  1. Two magnesium atoms react
  2. Magnesium has atomic number 2
  3. Each magnesium atom has 2 neutrons
  4. Two oxygen atoms are inside Mg

Question 9

What does the subscript 2 in H₂ mean?
  1. Two hydrogen atoms per molecule
  2. Two hydrogen molecules
  3. A charge of 2+
  4. Atomic number 2

Question 10

Which setup best tests mass conservation when a reaction makes gas?
  1. A sealed container on a balance
  2. An open beaker on a balance
  3. A heated crucible without a lid
  4. A flask vented through an open tube

Question 11

What does the arrow in a chemical equation mean?
  1. Reacts to form
  2. Is mixed with
  3. Is equal to
  4. Is dissolved in

Question 12

How many oxygen atoms are shown by 3CO2?
  1. 6
  2. 2
  3. 3
  4. 9

Question 13

Which word equation represents iron reacting with sulfur?
  1. iron + sulfur → iron sulfide
  2. iron sulfide → iron + sulfur
  3. iron + sulfur → iron sulfate
  4. iron + sulfur → sulfur dioxide

Question 14

\(250\,\mathrm{cm^3}\) is equal to how many \(\mathrm{dm^3}\)?
  1. \(0.250\,\mathrm{dm^3}\)
  2. \(2.50\,\mathrm{dm^3}\)
  3. \(25.0\,\mathrm{dm^3}\)
  4. \(0.025\,\mathrm{dm^3}\)

Question 15

Which formula contains the most atoms in one particle?
  1. CH4
  2. H2O
  3. CO2
  4. O2

Question 16

In \(\mathrm{N}_2 + 3\mathrm{H}_2 \to 2\mathrm{NH}_3\), how many hydrogen molecules react with one nitrogen molecule?
  1. 3
  2. 1
  3. 2
  4. 6

Question 17

A reaction uses 15 g of reactants and makes 9 g of one product. What is the other product's mass?
  1. 6 g
  2. 9 g
  3. 15 g
  4. 24 g

Question 18

What is a product in a chemical equation?
  1. A substance made by the reaction
  2. A starting substance
  3. A catalyst that remains unchanged
  4. A condition written above the arrow

Question 19

What does a chemical formula show?
  1. Its elements and their atom ratio
  2. The temperature of a reaction
  3. The colour of a chemical
  4. The mass of one sample

Question 20

Which equation for sodium reacting with chlorine is balanced?
  1. 2Na + Cl₂ → 2NaCl
  2. Na + Cl₂ → NaCl
  3. 2Na + Cl₂ → NaCl
  4. Na + Cl → NaCl₂

Question 21

How many different elements are present in NaOH?
  1. 3
  2. 1
  3. 2
  4. 4

Question 22

Why can a metal gain mass when heated in air?
  1. Oxygen atoms join the metal
  2. Metal atoms are created by heat
  3. Energy becomes extra metal
  4. The balance counts hot objects twice

Question 23

What is the formula of magnesium oxide?
  1. MgO
  2. Mg₂O
  3. MgO₂
  4. Mg₂O₂

Question 24

What is the formula of calcium chloride?
  1. CaCl₂
  2. CaCl
  3. Ca₂Cl
  4. Ca₂Cl₂

Question 25

What is a reactant in a chemical equation?
  1. A starting substance
  2. A substance made by the reaction
  3. A catalyst left unchanged
  4. A condition written above the arrow

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Review Formulae and Equations questions for Chemistry, with correct answers shown and coverage across chemical reactions as a rearrangement of atoms; writing formulae for simple compounds; word equations for common reactions.

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