Question

The mass of an atom is contained primarily by in its

Answer 1

Nucleus.

The nucleus contains the protons and neutrons, both of which are the two main sources of weight. There is also the electrons, but those do not contribute much weight.

Answer 2

Answer: Option (b) is the correct answer.

Explanation:

Atomic mass or mass number is defined as the sum of total number of both protons and neutrons present in an element.

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

Then it means that this atom contains 7 protons and the 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

As mass of an atom is dependent on number of protons and neutrons and, these sub-atomic particles (protons and neutrons) are present inside the nucleus of an atom.

This means that mass of an atom is concentrated on the nucleus of an atom.

Thus, we can conclude that the mass of an atom is contained primarily by in its nucleus.