The symbols below describe two isotopes of the element uranium. 

²³⁵₉₂ U  ²³⁸₉₂ U

a. State the meaning of the term isotope.

b. i. In what ways are these two isotopes of uranium identical?

ii. In what ways do they differ?

c. In a mass spectrometer uranium atoms can be converted to uranium ions, U²⁺. State the number of electrons present in one U²⁺ ion.