B) energy is absorbed by the reaction
is right answer.
Container which is heated
This problem is very easy to answer. You simply have to look at the subscripts of each element of the compound.
1. For caffeine, which has a molecular formula of C₈H₁₀N₄O₂, it contains 8 atoms of Carbon, 10 atoms of Hydrogen, 4 atoms of Nitrogen and 2 atoms of Oxygen.
2. For Iron(III) Sulfate, which has a molecular formula of Fe₂(SO₄)₃, it contains 2 atoms of Iron, 3 atoms of Sulfur, and 12 atoms of Oxygen.
Https://quizlet.com/18404690/chemistry-final-flash-cards/
here is a Quizlet I have for that