Which reaction is endothermic?
2brcl mc019-1.jpg br2 + cl2 + 29.3 kj
2h2 + o2 mc019-2.jpg 2h2o + 572 kj
c + o2 mc019-3.jpg co2 + 394 kj
n2o4 + 59 kj mc019-4.jpg 2no2

Which of these describes how heat is transferred by convection* a. sunlight travels through space without the aid of fluids or solids. b. warm air rises and takes the heat with it, eventually, it cools and sinks c. air at the equator rises and sinks at the poles. d. air molecules touch the warm ground, heating them up *not conduction