Scientists are comparing average octane ratings of different brands of gasoline. Which of the following methods is most likely to produce a biased
result?
A. Hire a scientist that works for a gasoline company.
B. Set criteria for judging how well the gasoline burns.
C. Use a team of scientists from different gasoline companies.
D. Let the brand of gasoline be the only variable.

um i think it might be a car?

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

plasma - state of matter made up of electrically charged particles