Answer: The symbol of this nuclide is [tex]_{19}^{40}\textrm{K}[/tex]
Explanation: The given element has atomic number of 19 and mass number of 40.
The atomic number of the element is equal to the number of protons and mass number is equal to the sum of number of protons and number of neutrons.
Thus atomic number of the element is 19 and the element is potassium which is represented by the symbol K.
[tex]_Z^A\textrm{X}[/tex] is the general representation where:
Z= atomic number
A= mass number
X= symbol of element.
Thus the representation is [tex]_{19}^{40}\textrm{K}[/tex]
