Answer:
mass number
Step-by-step explanation:
Here 35 is the mass number of sulphur. Mass number is equal to the number of protons and number of neutrons. The atomic number of S is 16. Atomic number is equal the number of protons which is equal to the number of electrons.
The electron configuration of S is 1s²2s²2p⁶3s²3p⁴
Number of neutrons in S is the difference between mass number and atomic number, which is
Number of neutrons = mass number - atomic number = 35-16 = 19