For starters, atoms are the basic building blocks of matter- they make up elements, molecules and compounds. Elements most often combine with other elements as compounds. Whilst molecules are particles found in both elements and compounds. I hope that wasn't too confusing, but bottom line is that they are all linked together in this way! Helpful? :)
I think the answer is melting
A mutation is a change in trait. For example people who are lactose intolerant are normal, but people that can can drink milk without a problem have mutated. Hopefully this makes sense and helped.
B. Two disaccharides bonded together