The isotope of iodine with mass number 131 is often used in medicine as a radioactive tracer. write the symbol for this isotope indicating both mass number and atomic number.

Iodine - 113, means iodine with mass number 113

To specify a particular isotope, add superscript and subscript on the left of symbol.

The superscript indicates the mass number (number of protons + neutrons)

The subscript indicates the atomic number (number of protons)

The iodine - 113 is writen

113
      I        [this the letter i]
 53

superscript 113 on the left ofd the symbol is the mass number = protons + neutrons

I is the symbol (letter i)

subscript 53 on the left of the symbol is the atomic number (number of protons)

Do u have the n? or maybe the m?

Okay well gravitational energy is matter forced by gravity making energy though the kinetic energy then the electric energy produces electricity from the kinetic energy and the kinetic energy gets its energy from the gravitational energy. was that the answer you wanted or something else?