Multiple choice

Which of the following statements is TRUE about chemical reactions?

  1. All chemical reactions are reversible.

  2. All chemical reactions release heat during decomposition of molecules.

  3. Each chemical reaction is carried out by breaking bond between the molecules.

  4. All chemical reactions do not burn and dissolve.

  5. All of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chemists are concerned with both physical and chemical change, and the energy associated with each. Chemical reactions involve the making and breaking of covalent bonds and these transformations have energy consequences.The sum of all the bond energies of a molecule can therefore be considered its atomization energy, i.e. the energy required to break the molecule completely into its component atoms.

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