Which is the correct symbol for an isotope of iodine with 53 protons and 78 neutrons?

Question

Responses
A 78I5378I53
B 131I131I
C 53I53 I
D 131I

Answer 1

The correct symbol for an isotope of iodine with 53 protons and 78 neutrons can be determined as follows:

1. The number of protons (atomic number) identifies the element. In this case, iodine has 53 protons.
2. To find the mass number of the isotope, you add the number of protons and neutrons together: Mass number = Protons + Neutrons = 53 + 78 = 131.

Therefore, the isotope of iodine can be represented as \( ^{131}_{53}\text{I} \) or simply \( \text{I}-131 \).

Looking at the response options, D (131I) is the correct representation of the isotope.

So, the answer is D 131I.