How many neutrons does element x have if its atomic number is 23 and its mass number is 90?

Neutrons =atomic mass number - atomic no

So 90 - 23= 67 Neutrons

Have a good day! ;)

The number of neutrons is 67

As we know that the atomic number is the number of protons. If we subtract the atomic number from the mass number, we can actually find the number of neutrons.

So

Number of neutrons = Mass number - atomic number

Neutrons = 90 - 23 = 67

i think it's letter a.