Solutions For Admission Assessment Exam Review Chapter F Problem 6CPT

The sum of the neutron and proton numbers is called as mass number. Neutron number does not give any atomic number.

Hence, the option A is wrong.

The number of electrons in the atom is not constant for the same element. Hence, it is not give any atomic number.

Hence, the option C is also wrong.

Number of isotopes depends on the proton and neutron number. Hence, it is also not equal to atomic number.

Hence, the option D is wrong.

The number of protons in any atom is constant for the same element. It is defined as the atomic number.

Hence, the correct option is.