The answer to this question is 5
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1) Decomposition reactions. In this type of reaction, a compound is broken down into simpler compounds.

Option B is a decomposition reaction
B) ____ KClO3 → ____ KCl + ____ O2
Explanation:
To delineate the the nature of the bonds that would be formed between the two elements, let us first write the electronic configuration of the two species;
Be = 2, 2
F = 2, 7
Beryllium is a metal with two valence electrons whereas fluorine is a halogen with seven valence electrons.
When Be loses two electrons it becomes isoelectronic with He;
Be → Be²⁺ + 2e⁻
Also, when fluorine gains an electron, it becomes isoelectronic with Ne;
F + e⁻ → F⁻
This loss and gain of electrons between the two elements creates an electrostatic attraction them and they enter into an electrovalent bond.
Hence;
Be²⁺ + 2F⁻ → BeF₂
The activation energy is the minimum amount of energy that particles must have in order for them to participate in a chemical reaction. During chemical reactions bonds are broken and formed. Particles must collide with sufficient energy in order for the initial bonds to be broken. The activation energy is that that initial minimum energy that the particles can have in order for the bonds to be broken. Stronger bonds would require more energy to be broken and therefore the activation energy for such would be higher.