C. a nucleus
because they orbit it
Answer:
There's a separate chemical reaction happening at the positive electrode, where incoming electrons recombine with ions taken out of the electrolyte, so completing the circuit. The electrons and ions flow because of the chemical reactions happening inside the battery—usually two of them going on simultaneously.
Explanation:
option (B) is right
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.
Answer:
it is b just trust me man I know