What is a substance made from one type of atom

Si, H, He

Explanation:

A substance of only one type of atom would be a pure substance from any of the elements in the period table. This could be nitrogen, N2, which is easily isolated, or gold, Au, which tends not to form compounds with other elements.

On earth, we have been able to refine silicon, Si, to a highly pure state. This may be the best example of a substance of only one type of atom. There may be other better answers such as some parts of a star contain only hydrogen, H, or helium, He.

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