C2H4(g) + 302(g) → 2CO2(g) + 2H20(i) H =-1411 kJ/mol The equation above can be classified as
A endothermic; H is positive
B
exothermic; H is negative
exothermic; H is positive
D endothermic; H is negative

If many scientists conduct the same or similar experiments, and all obtain similar results, a can be written, which is a generally agreed-upon statement that explains and predicts how a natural phenomenon works.