The is the best part of an experiment that is not being tested and it used for comparison

Which of the following contributes to the structural rigidity of cellulose? adjacent glucose polymers are stabilized by hydrogen bonding. glucose residues are joined by (α1→4) linkages. cellulose is a highly branched molecule. the conformation of the glucose polymer is a coiled structure.

An alpha particle is: a hydrogen atom a nucleus of helium two neutrons an electron

How does science use models to gain a better understanding of concepts?