<em></em>hydrogen #1 carbon #6 nitrogen #7 oxygen #8 Phosphorus #15 Sulfur #16 Selenium #34
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.
The balanced chemical equation for the following equation is:
Ca(OH)
2
+CO
2
⟶CaCO
3
+H
2
O
The answer to your question big man would be E
Answer and explanation;
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