Respuesta :

Answer:

55

Explanation:

mass number is neutron + proton

25+30

=55

note that the atomic number is =proton

The value of the mass number is 55.

The formula for mass number is as follows:-

[tex]Mass number = Number of protons+Number of neutrons[/tex]

Substitute 25 for number of protons and 30  for number of neutrons in the above equation as follows:-

[tex]Mass number=25+30\\=55[/tex]

Hence, the value of the mass number is 55.

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