Question

write the atomic symbol (including the atomic number) for the isotope of iodine with 76 neutrons. use the format $_z^a x$ in your answer.

Explanation:

Step1: Find atomic number of iodine

From periodic - table, atomic number of iodine ($I$) is 53.

Step2: Calculate mass number

Mass number ($A$) = number of protons+number of neutrons. Protons = atomic number = 53, neutrons = 76. So $A=53 + 76=129$.

Answer:

$^{129}_{53}I$