Which of the following best describes an electron? For science

The statement electrons reside in the nucleus best describes an electrons in the given statements. The electrons are the subatomic particles which contribute negative charge to the atom and also balances protons and neutrons in an atom. They are very much needed to conduct electricity

Explanation: that is my answer because electrons are made of electricity

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally