The mass number of an atom is 15, and its atomic number is 7. the atom probably 8 neutrons in the nucleus. about as much mass in electrons as in protons. at least 15 electrons. 7 units of negative charge in the nucleus. 7 electrons in the nucleus.

Option (a) is the correct answer.

Explanation:

Atomic number is the sum of only total number of protons present in an element. Whereas mass number is the sum of total number of both protons and neutrons present in an element.

For example, given atom has mass number as 15 and its atomic number is 7.

Therefore, number of neutrons present in it will be calculated as follows.

                    Mass number = no. of protons + no. of neutrons

                         15 = 7 + no. of neutrons

                    no. of neutrons = 15 - 7

                                               = 8

Thus, we can conclude that the given atom contains 8 neutrons in the nucleus.