Which household item uses radiation in a beneficial way?
a. conventional ovens
b. smoke detectors
c. electric air filters
d. computers and tv sets

a. a primary source combines several different accounts of an event. b. a primary source generally benefits from having been written after an event.

explanation:

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)

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