An iron atom has an atomic mass of 56. Its atomic number is 26. How many neutrons does the iron atom have?

30

Explanation:

atomic mass = proton number + neutron number

proton number is also atomic number

explanation:

since this is put under health, i would define "ethical (medical) behavior" the way the oath for doctors is recited.   "first do no harm."

but the term in general means when given a choice between right and wrong, we should always choose right. if we do, then we are practicing ethical behavior.

indium, and thallium have three electrons i think