Question

Arrange the isotopes of sulfur and phosphorus in order of decreasing number of neutrons.

Rank the isotopes from most to fewest neutrons. To rank items as equivalent, overlap them.

Answer 1

I do not believe you're asking this...
OK. Sulfur has a total of 24 isotopes. Every isotope has 16 protons and the number of neutrons ranges from 10 to 33 inclusive.
Phosphorus has a total of 23 isotopes. They have 15 protons, and between 9 and 31 neutrons inclusive. So here we go.

S-49
S-48
S-47, P-46
S-46, P-45
S-45, P-44
S-44, P-43
S-43, P-42
S-42, P-41
S-41, P-40
S-40, P-39
S-39, P-38
S-38, P-37
S-37, P-36
S-36, P-35
S-35, P-34
S-34, P-33
S-33, P-32
S-32, P-31
S-31, P-30
S-30, P-29
S-29, P-28
S-28, P-27
S-27, P-26
S-26, P-25
P-24

If you're looking for STABLE isotopes, then the list is much smaller.
S-36
S-34
S-33
S-32, P-31

Answer 2

Rank of the isotopes from most to fewest neutrons:

S-36, P-35

P-33

P-32

S-32, P-31

Step-by-step explanation:

The following options are missing:

S-36

P-35

S-32

P-33

P-32

P-31

Sulfur has 16 protons then S-36 has 36 - 16 = 20 neutrons and S-32 has 32 - 16 = 16 neutrons.

Phosphorus has 15 protons, then P-35 has 35 - 15 = 20 neutrons, P-33 has 33 - 15 = 18 neutrons, P-32 has 32 - 15 = 17 neutrons and P-31 has 31 - 15 = 16 neutrons.