Which one of the three bond types distinctly different form the other two? explain why so?

The metallic bond is distinctly different from covalent and ionic bonds. Metallic bonding involves atoms sharing electrons among many atoms. Covalent and ionic bonds depend on the electronegativity differences between atoms and the sharing of electrons to a greater or lesser extent between just a few atoms. 

35 KJ.

Explanation:

The activation energy is the minimum energy that must be overcome for a reaction to take place.

In the diagram given above, the activation energy lies between the energy of the reactants and that at the peak.

Thus we can calculate the activation energy as follow:

Energy of reactants = 30 KJ

Energy at the peak = 65 KJ

Activation energy =..?

Activation energy = Energy at the peak – Energy of reactants

Activation energy = 65 – 30

Activation energy = 35 KJ

Therefore, the activation energy of th reaction is 35 KJ