The best answer for the question above would be the chloroflourocarbons or the CFCs. These chloroflourocarbons or CFCs are the ones responsible for the depletion of the ozone - which leads to leaving a hole in its layer. These gases eat out the ozone layer and allows harmful UV rays of the sun to come in the Earth.
It would be a physical change. It’s still water just in a different physical form. If it was a chemical change, it would no longer be water. For example, when the ice melts back into water...it’s still water.
In total dominance, the phenotype sees only one allele in the genotype. Both alleles in the genotype are seen in the phenotype during codominance. In incomplete dominance, in the phenotype, a mixture of the alleles in the genotype is seen.