In the diagram, which letter represents the activation energy?

A

B

C

D

The letter that represents the activation energy from the diagram is letter A.

A chemical reaction occurs only when there is collision between the particles of reactants.

These colliding particles become activated with increased kinetic energy.

Activation energy is the energy barrier that must be overcome before a reaction takes place.

From the diagram,

C is the reactants

D is the products

B is the heat of reaction

While A is the activation energy.

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C

Explanation:

This is the amount of energy we start on.

Hope this helped

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explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.