Cul (s) --> represents its state which means solid, Here Valency of copper is 1 so its cuprous.
<span>Fe2O3--> Ferric Oxide is a solid. Here valency of Fe is +3 so its Ferric </span>
<span>CoF2--> Cobalt Flouride is a solid</span>
<span>FeO --> Ferrous Oxide is a solid. Here valency of iron is +2 so its Ferrous. </span>
Answer:
Astatine is a halogen with several isotopes that all have short half-lives.
Which of the following combinations of mass number and neutrons are possible as isotopes of astatine? Choose one or more:
i) A = 211, n = 127
ii) A = 210, n = 125
iii) A = 220, n = 134
iv) A = 207, n = 122
v) A = 209, n = 124
Explanation:
The mass number is the sum of the number of protons and the number of neutrons in an atom.
Atomic number of At(astatine ) =85
That means it has --- 85protons.
Its mass number A=210
Hence, the number of neutrons in At are:

Second option:
ii) A=210 , n=125 is the answer.
D. Model number 2
Hope this helps!! (:
I'm pretty sure it's A, but then again I'm only in 8th grade. Sorry if this doesn't help:(