The atomic number of manganese is 25; its mass number is 55.
how many neutrons does an atom of manganese have in its nucleus?

a) 25 b) 80 c) 30 d) 55

c) 30

Explanation:

In an atom , the relation between the subatomic particles of the atom are given as follows -

For a neutral atom ,

Atomic number = number of protons = number of electrons ,

Mass number = number of protons + number of neutrons,

Hence , from the given information of the question,

Atomic number of Manganese = 25 ,

mass number of Manganese = 55 ,

Now, to calculate the number of neutrons , the above relation can be used -

Mass number = number of protons + number of neutrons,

Rearranging ,

number of neutrons = Mass number - number of protons

substituting the respective values ,

number of neutrons = 55 - 25 = 30 .

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates