Question

When magnesium is burned in oxygen the product formed becomes heavy why?

Answer 1

Because when magnesium is burnt the residue that is left is magnesium oxide which is solid amd thus become heavy

Answer 2

When it burns in oxygen a heat created during this reaction, And after heat we get magnesium oxide as product which is solid this is also a reason but we can say in this compound the weight of magnesium increases due to oxygen.