Which reaction is endothermic?
h2(g) + ½ o2(g) → h2o(g), δh = -57.82 kcal
½n2(g) + o2(g) + 8.1 kcal → no2(g)
½n2(g) + 3/2h2(g) → nh3(g) + 11.0 kcal
c(diamond) + o2(g) → co2, δh = -94.50 kcal

the correct answer is b. a strong acid completely dissociates to its ions when dissolved in water. completely dissociates to and ions. a is incorrect because does not fully ionize to and ions and some remain as the compound . c and d are incorrect because, and do not fall into the category of bronsted lowry acids. a bronsted lowry acid is a proton donor and since both molecules do not have a proton to donate they are not bronsted lowry acids. likewise,   if we use the lewis acid definition, they cannot be acids. a lewis acid is an electron pair acceptor. both and have a complete octet so can not accept any electrons which disqualifies them as acids.