1)Delta H=(Delta H of reactants)-(Delta H of products)
2)And we know CO have 3 bond CO and CO2 have 2 bond that each of them are 2 bond, please see the picture!
so lets answer it:

Answer:
Ag 0 is the reducing agent.
Explanation:
Reducing -> gaining electrons
Oxidizing -> losing electrons
Ag lost electrons (became more positive) since it went from a 0 charge to a +1 charge. Therefore it was oxidized. Ag+ is the oxidized product. Reactants that create an oxidized product are called reducing agents. This would make Ag 0 the reducing agent in this reaction.
Answer: Option (b) is the correct answer.
Explanation:
A synthesis reaction is the reaction in which two compounds or atoms combine together to result in the formation of a single compound.
For example, 
Thus, here CaO and
combine together to result in the formation of calcium carbonate compound. Therefore, it is a synthesis reaction.
Therefore, we can conclude that the most likely products of Cao + co2 → CaCO3 reaction.
Answer:
accretion
Explanation:
the coming together and cohesion of matter under the influence of gravitation to form larger bodies.