Which of the following reactions is endothermic? h2(g) + ½o2(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 reactions: 1/2n2(g)+ o2(g) ⇒ no2(g) +8.1kcal and 1/2n2+3/2h2(g)⇒ nh3(g)+11.0kcal are both endothermic, that is, they react by gaining energy thus the positive enthalpy notation.

the link still does not work even when adding it to the url bar

explanation:

they it depends on if one believes about radioactivity, they make a geiger counter beep but maybe it was going to beep anyway electronics do wierd things all the time or it was programmed to beep near certain metals.