Which atomic property is different in each isotope of an element? number of protons number of electrons charge mass number atomic number

Why are the trends and exceptions to the trends in ionization energy observed?

Ab c or d ? i’m not sure what the answer is

Acm ruler with main graduations from 1 to 10 from left to right there are 10 secondary graduations between each of the main graduations there is a line that begins. at the left end of the ruler 10 secondary graduations to the left of the “1 main graduation the right end of the line ends on the eighth secondary graduation to the right of 3 how long is the line