Which of the following must be the same for two isotopes of an element? a. the number of neutrons b. the atomic number c. the mass d. the charge answer is the atomic number

B. The atomic number. This is because the atomic number is the same as the number of protons an element has, and the number of protons defines an element.

The correct answer is c. orbital shape. "the angular momentum quantum number l describes the shape of an orbital. it corresponds to each orbital type, i.e. (0,1,2,−1)=(s,p,d,f,g,"