Answer
The nuclear equations are written below:
Work Step by Step
When a positron is emitted from the nucleus of a radioactive element, the atomic number of that nuclide is decreased by 1 unit but mass number does not change. So, the daughter nuclide will have atomic number less than 1 unit but the mass number will be same as parent nuclide.
Positron is represented as symbol 'e' with '+1' on left subscript and '0' on left superscript.
Now, let's write every nuclear equation.
Co-55 (atomic number = 27) is converted to Fe-55 (atomic number =26) after positron emission.
Na-22 (atomic number = 11) is converted to Ne-22 (atomic number = 10) after positron emission.
F-18 (atomic number = 9) is converted to O-18 (atomic number = 8) after positron emission.
When writing nuclear equation, all the elements are represented in symbol (Process to write nuclide in the form of symbol: Write chemical symbol of that element, write atomic number on the left subscript position and mass number on the left superscript position).
After writing the nuclear equation, the total mass number (sum of mass number of each nuclide on the left side) on the left side will be equal to the total mass number on the right side (sum of mass number of each nuclide on the right side). Similarly, total atomic number on the left side will be equal to the total atomic number on the right side.
General form of nuclear equation after positron emission is as follows
