Where are valance electrons located in an atom?

Isotopes of the same element have differ in their

Why do some dna fragments move farther than others during gel electrophoresis? a. because their shapes are different b. because they are different types of molecules c. because the samples are different colors d. because their masses are different

As kate is moving down the hill, what type of energy does she have? a. sound energy b. electrical energy c. light energy d. mechanical energy