Classify reactions: synthesis, decomposition, replacement, combustion

Answer Key - Grade 10 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Ethane has 2 carbon and 6 hydrogen atoms and burns completely to CO₂ and H₂O. How many oxygen atoms end up in the products of one molecule, Bo?

   7 O atoms
2. 2.

   Butane has 4 carbon and 10 hydrogen atoms and burns completely to CO₂ and H₂O. How many oxygen atoms end up in the products of one molecule, Esme?

   13 O atoms
3. 3.

   2 H₂ + O₂ → 2 H₂O gives off heat and light. Which two types describe it, Jun?

   • Single and double replacement
   • Decomposition and combustion
   • Synthesis and combustion
4. 4.

   Why is CH₄ + 2 O₂ → CO₂ + 2 H₂O not a synthesis reaction, Kira?

   • Its products are elements
   • It has a single reactant
   • It makes two products, not one
5. 5.

   Which equation is a decomposition, Luz?

   • 2 H₂O₂ → 2 H₂O + O₂
   • Zn + CuSO₄ → ZnSO₄ + Cu
   • 2 H₂ + O₂ → 2 H₂O
6. 6.

   Milo says Zn + CuSO₄ → ZnSO₄ + Cu is double replacement. Agree or disagree?

   • Disagree: an element replaces another
   • Agree: both of the reactants are compounds
   • Agree: zinc sulfate is a compound
7. 7.

   Noah says AgNO₃ + NaCl → AgCl + NaNO₃ is single replacement. Agree or disagree?

   • Disagree: two compounds trade partners
   • Agree: silver replaces sodium on its own
   • Agree: one product is a solid
8. 8.

   Pia says iron rusting in damp air is combustion because it uses oxygen. Agree or disagree?

   • Agree: rust is a kind of ash
   • Agree: anything that uses oxygen is burning
   • Disagree: rusting is slow, with no flame
9. 9.

   Which balanced equation shows ethane, C₂H₆, burning completely, Tala?

   • 2 C₂H₆ + 7 O₂ → 4 CO₂ + 6 H₂O
   • C₂H₆ + 3 O₂ → 2 CO₂ + 3 H₂O
   • C₂H₆ → 2 C + 3 H₂
10. 10.

    In the double replacement of CaCl₂ with Na₂CO₃, what are the products, Zee?

    • Ca₂CO₃ + NaCl
    • CaCO₃ + 2 NaCl
    • CaNa₂ + CO₃Cl₂