Which of the following is true for the reaction below? co2(g) + 393.5 kj c(s) + o2(g)
it is endothermic and the ∆h = +393.5 kj.
it is endothermic and the ∆h = -393.5 kj.
it is exothermic and the ∆h = +393.5 kj.
it is exothermic and the ∆h= -393.5 kj.
this reaction will not occur.

Reacting masses1 calcium carbonate breaks down on heating to produce calcium oxide and carbondioxide gas.caco3 + cao + co2a student heats 15 g of calcium carbonate strongly in a crucible.relative atomic masses (a): ca = 40, c = 12, o = 16.calculate the mass of calcium oxide produced by this reaction.(5 marks)