Coplanar circles that have a common center are called

Concentric circles

Step-by-step explanation:

They are co-planar, so they lie in the same two-dimensional space.  Since they share a common center, they would only differ in radius length.  What we would have is a bunch of circles withing other circles sharing a common center.  We call those concentric circles

Con- with

Centric - having to do with the center

answer4 to the second power is 16

and 4 to the third power is 64,

chemists are often responsible for designing a chemical reaction and analyzing the products obtained from it. one significant part of designing a chemical reaction is determining the amount of each reactant that is needed and the amount of each product that will be produced. in order to do so, chemists use stoichiometry, the quantitative relationships between reactants and products.