Answer:
283.725 kJ ⋅ mol − 1
Explanation:
C(s) + 2Br2(g) ⇒ CBr4(g) , Δ H ∘ = 29.4 kJ ⋅ mol − 1
Br2(g) ⇒ Br(g) , Δ H ∘ = 111.9 kJ ⋅ mol − 1
C(s) ⇒ C(g) , Δ H ∘ = 716.7 kJ ⋅ mol − 1
4*eqn(2) + eqn(3) ⇒ 2Br2(g) + C(s) ⇒ 4 Br(g) + C(g) , Δ H ∘ = 1164.3 kJ ⋅ mol − 1
eqn(1) - eqn(4) ⇒ 4 Br(g) + C(g) ⇒ CBr4(g) , Δ H ∘ = -1134.9 kJ ⋅ mol − 1
so,
average bond enthalpy is
= 283.725 kJ ⋅ mol − 1
Answer:
5.25 moles.
Explanation:
The decomposition reaction of NaN₃ is as follows :

We need to find how many grams of N₂ produced in the process.
From the above balanced chemical reaction, we conclude that the ratio of moles of sodium azide and nitrogen gas are 2 : 3.
2 moles of sodium azide decomposes to give 3 moles of nitrogen gas. So,
3.5 moles of sodium azide decomposes to give
moles of nitrogen gas.
Hence, the number of moles produced is 5.25 moles.
Sun isn't actually planet but star. Really big ball made of gases. Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%). Sun is the biggest object in our Solar System. It's 99.86% of the total mass of the Solar System.
... wikipedia is really grat if you have questions like that ;)