Answer:
60 neutrons
Explanation:
We are given that the atomic number of an element X is 25 and its mass number is 85 and we are find the number of neutrons this element has.
We will use the following formula to find the number of neutrons:
Neutrons = Atomic mass number - Atomic number
So substituting the given values in the above formula to get:
Number of neutron = 85 - 25 = 60
Therefore, element X has 60 neutrons.