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MDCAT
Chemistry
2008

Chemistry · Thermochemistry

Work through this past-paper style MCQ, then read the full explanation. Practice more chemistry questions on mMCQ with adaptive practice and topic analytics.

Question

Which of the following formation is endothermic reaction?

Options
  • A

    2 H2 (g) + O2 (g) -> 2H2O (l)

  • B

    C(s) + O2 (g) -> CO2(g)

  • C

    N2(g) + O2 (g) -> N2O2 (g)

  • D

    None of these

Explanation

Because heat is absorbed in this reaction. All the other reactions are exothermic as the heat is released during the process.

This is an exothermic reaction. The formation of water (H2O) from hydrogen gas (H2) and oxygen gas (O2) releases heat energy and is accompanied by a decrease in enthalpy. Therefore, this reaction is not endothermic. 

This is an exothermic reaction. The combustion of carbon (C) to form carbon dioxide (CO2) releases heat energy and is accompanied by a decrease in enthalpy. Therefore, this reaction is not endothermic. 

Because heat is absorbed in this reaction. All the other reactions are exothermic as the heat is released during the process. 

Incorrect option. option c) is correct.

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Tagged under Chemistry · Thermochemistry · 2008