What distinguishes a chemical change from a physical change?

What is the next step in muscle contraction after the actin changes shape? (apex)

Indicate the coat color and the proportion of offspring with that color for each of the following crosses of rabbits. assume all are homozygous. chinchilla x chinchilla 1/2 agouti, 1/2 chinchilla 3/4 agouti, 1/4 chinchilla all chinchilla

Which two criteria must be met before scientist can use radiocarbon dating? explain your answer