Answer
(a) $^{186}_{74}$W
(b) $^{201}_{80}$Hg
(c) $^{76}_{34}$Se
(d) $^{239}_{94}$Pu
Work Step by Step
"$Z$" stands for the atomic number whereas "$A$" stands for the mass number. The atomic number is written as a subscript for the element symbol whereas the atomic mass is written as a superscript also to the left of the chemical symbol.
(a) The atomic number given is for that of tungsten, W. The symbol for this isotope of tungsten is $^{186}_{74}$W.
(b) The atomic number given is for that of mercury, Hg. The symbol for this isotope of mercury is $^{201}_{80}$Hg.
(c) The atomic number given is for that of selenium, Se. The symbol for this isotope of selenium is $^{76}_{34}$Se.
(d) The atomic number given is for that of plutonium, Pu. The symbol for this isotope of plutonium is $^{239}_{94}$Pu.
