A substrate molecule fits into the active site of an enzyme because of a match of _____. Chemistry homework help

1. A substrate molecule fits into the active site of an enzyme because of a match of _____. 

A. Number of atoms

B. Molecular Mass

C. Molecular Shape

D. Melting points

2. A sample of a metal on the atomic scale would best be described as a network of positive ions surrounded by free-flowing _________ .

A. Electrons

B. Protons

C. Neutrons

D. Atoms