The main pieces of evidence that an exothermic reaction has occurred is an increase in temperature due to the release of energy, a release of energy in the form of light, or a release of gas.
Answer:
4Ba(CO3) -> 4BaO2 + 2CO2
Explanation:
I looked at the oxygens to balance this. Ba(CO3) normally has 3 oxygens. BaO2 and CO2 have 4 oxygens total. The common multiple of 3 & 4 is 12. So there should be 12 oxygens on both sides. Then I just found the coefficients that would give 12 oxygens on both sides and can balance the rest of the atoms.
Energy lost to condense = 803.4 kJ
<h3>Further explanation</h3>
Condensation of steam through 2 stages:
1. phase change(steam to water)
2. cool down(100 to 0 C)
1. phase change(condensation)
Lv==latent heat of vaporization for water=2260 J/g

2. cool down
c=specific heat for water=4.18 J/g C

Total heat =

D is the correct answer
every other option contains an element