Question

a radioactive nuclide that is used for radiation therapy for cancer has 33 neutrons and a mass number of 60. which is the correct symbol for this nuclide?
27 60 co
33 60 co
60 33 co
60 27 co

Explanation:

Step1: Recall mass - number formula

The mass number ($A$) is the sum of protons ($Z$) and neutrons ($N$), i.e., $A = Z+N$.

Step2: Calculate the number of protons

Given $A = 60$ and $N = 33$. We can find $Z$ using the formula $Z=A - N$. So, $Z=60 - 33=27$.

Step3: Identify the element

The atomic number ($Z$) determines the element. An element with $Z = 27$ is cobalt (Co).

Step4: Write the nuclide symbol

The nuclide symbol is written as $^{A}_{Z}X$, where $A$ is the mass number and $Z$ is the atomic number and $X$ is the chemical symbol of the element. So the symbol for this nuclide is $^{60}_{27}Co$.

Answer:

$^{60}_{27}Co$ (corresponding to the last option in the multiple - choice list)