Answer:
Neon is the elements with same number of neutrons as of Fluorine.
Step-by-step explanation:
Mass number of an element is the sum of atomic number of element and number of neutrons.
atomic number is number of protons.
The atomic number of given elements are
Neon: 10
Oxygen: 8
Sodium: 11
Nitrogen: 7
Fluorine: 9
The number of neutrons will be
Fluorine-19
Number of neutrons =19-9=10
Neon-20 :
Number of neutrons = 20-10 = 10
Oxygen-19:
Number of neutrons = 19-8 = 11
Sodium-22
Number of neutrons = 22-11 = 11
Nitrogen-16
Number of neutrons = 16-7 = 9
thus Neon is the elements with same number of neutrons as of Fluorine.