Answer and Explanation:
a) Mercury (II) Oxide is given by the chemical formula:
[tex]\rm PbO[/tex]
Since we are given that the mercury ion has a +2 charge, and we can assume that the oxygen ion has a -2 charge, both atoms have a 1:1 ratio.
Putting this into a decomposition reaction, we get:
[tex]\boxed{\rm 2PbO_{(s)} \to 2Pb_{(l)} + O_{2(g)}}[/tex]
b) The red arrow in the diagram shows the peak of the potential energy of the reactant-product system. This is also known as the activation energy of the reaction.
[tex]\boxed{\rm activation\ energy}[/tex]
c) In the transition state, the reaction has not gone to completion. Therefore, there will be a mixture of some solid and some liquid.
d) The reaction is endothermic because the potential energy of the products is greater than that of the reactants. (The "hill" ends higher than it starts.)