Answer
$^{77}_{34}Se^{-2}$
Work Step by Step
We can determine the atomic number and the required element as follows:
As we know that
Atomic number=mass number- No. of neutrons
We plug in t he known values to obtain:
$Atomic \space number=77-43=34$
Thus, the element having atomic number 34 is Se and we can represent it as $^{77}_{34}Se^{-2}$
