Respuesta :

The mass number of this atom having 53 protons, 78 neutrons, and 54 electrons will be 131.

In the field of science, we can describe a mass number of an atom as simply a measure of the protons and neutrons that are to be found in the nucleus of an atom. In chemistry, the mass number is denoted by the letter 'A'.

In the above-mentioned case, the number of protons of the atom is 53 whereas the number of neutrons is 78.

In order to calculate the mass number, we will add the number of protons and neutrons. As the result of the addition of 53+78 is 131 hence, the mass number will be 131.

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