posted by lucas .
An element has an ion with +2 charge.It has 38 electrons and 51 neutrons. write the nuclear symbol for the element.
The question could have been worded more clearly. It isn't completely clear whether "it" refers to the ion or to the element. My response below assumes the ION has 38 electrons.
The ion has 38 electrons and with a +2 charge for the ion it must have had 40 initially. Look up element #40 in the periodic table. The mass number of number of protons + number of neutrons.