Because it contains hydrogen which isn't formed by a special process like oxygen
The "Dawn horses" were actually not related to horses! Recent studies of fossils found that "Dawn Horses" were buried in the same rock layers as modern horses! evolutionists were shocked at first but then decided that the "Dawn horse" was related to rabbits! Now to answer your question no one really knows why they went extinct. Evolutionist believe they changed into rabbits and Creationists (people who believe God created the universe and that evolution is incorrect) believe they died out due to climate changes after the global flood of Noah.
Supplementary angles add up to 180, so
6x+60+90 = 180 and solve for x
6x= 30
x=5
Number of moles of FeCl2 used = mass/ molar mass
Number of moles = 507/126.751 = 4.
If one mole of Fe reacts with two moles of sodium
Then 4 moles of Fe produces 8 moles of sodium.
Number of moles of sodium = mass/molar mass
Molar mass of sodium chloride = 23 +35.5 = 58.5 g/mol
Hence mass = 8 * 58.5 = 468 g. Hence Option A.