The enthalpy changes, δH , for three reactions are given. H2(g)+12o2(g)ca(s)+2h+(aq)cao(s)+2h +(aq)⟶h2o(l)⟶ca2+(aq)+h2(g)⟶ca2+(aq )+h2o(l)δH=−286 kj/molδH=−544 kj/molδH=−193 kj/mol using hess's law, calculate the heat of formation for cao(s) using the reaction shown. Ca(s)+12o2(g)⟶cao(s).

Spider crabs live in the shallow regions of the ocean floor. algae tend to grow on the surface of spider crabs. the algae provide the crabs protection from predators by camouflaging them. the spider crabs give the algae shelter. what does this description suggest? 1. the algae are parasites of the spider crabs. 2. the algae and the spider crabs have a mutualistic relationship. 3. the spider crabs are commensals, and the algae are parasites. 4. the spider crabs benefit from the algae living on them. 5. the spider crabs are parasites of the algae.