About stars! i will give special to those who me give the right answer!

12.From what I've read, white stars are hotter than red ones. But a white dwarf would have just heavy elements to fuse, so shouldn't it be less bright? 

13. Neither of those answers is correct, it's actually 4.8 (even check with google)

14. (B) Vega

15.  M2lab is its Spectral type
      (here are some extra facts :)
      Magnitude: 0.42      Radius: 820.9 million km (1,180 R☉)      Surface temperature: 3,500 K      Absolute magnitude: -5.85      Mass: 1.531 × 10^31 kg (7.7 M☉)      Did you know: Betelgeuse is the fifth-nearest supernova candidate by              distance (640 light years)

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen

Answertrue;