6. Which ion is written first in an ionic compound? Second? 7. When are parentheses used in ionic compound formulas?
8. What type of bond is between :Jodium and chlorine in sodium chloride
(NaCl)?
9. What type of bond is between carbon and oxygen in carbon monoxide
(CO)?

it's c. elements are placed in rows based on how may valencies electrons have.

because of all the things that happen around the us, many people get into arguments which sadly could get physical, but we should actually make a change for that.

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