Aluminium Sulfide
According to rules the positive specie is named first and the negative specie is named last.
Answer is: the average atomic mass is 232.
ω₁ = 20% ÷ 100%.
ω₁ = 0.20.
ω₂ = 80% ÷ 100%.
ω₂ = 0.80.
Ar₁ = 120 (number of protons) + 120 (number of neutrons).
Ar₁ = 240.
Ar₂ = 120 + 110
.
Ar₂ = 230.
Average atomic mass of atoms of bolognium =
Ar₁ · ω₁ + Ar₂ · ω₂.
Average atomic mass of atoms of bolognium = 240 · 0.2 + 230 · 0.8.
Average atomic mass of atoms of bolognium = 48 + 184.
Average atomic mass of atoms of bolognium = 232.
I believe the answer you are looking for is the 4th one.
Reactivity trends of halogen:
1) Melting point and boiling points increased down the
group
2) Colour becomes darker.
E.g. Fluorine (pale yellow)
Chlorine (yellowish-green)
Bromine (reddish-brown)
Iodine (purplish-black)
Astatine (black)
3) The reactivity decreases down the group.
Reactivity:
F > Cl > Br > I > At
