Question

I have a question about isotopes, i understand what they are however i can't answer this question for school. it doesn't seem like i have enough info to answer the question

Write the symbols for the following isotopes.
Its atoms contain 50 electrons and 70 neutrons
Express your answer as an isotope.

Answer 1

it is most likely that the isotope isnt charged. So i would say there are equal amounts of neutrons as protons.
50 protons + 70 neutrons+ 120 atomic mass of isotope and 50 is the atomic number so i believe its Sn