If you had a beaker full of black powder which of the following could you have?
a. mixture
b. element
c. compound
d. any of these is possible.

a. mixture

Explanation:

A black powder probably represents a mixture of several dark colored elements, or several elements that reacted and formed a black colored mixture.

Mixture is the union of two or more different substances (regardless of whether they are simple or compound). It has different and variable (non-fixed) physical characteristics (melting point, boiling point, density, toughness, etc.) compared to its constituent substances.

it is stable as it is in group 0 which have full outer shells of electrons

a is the correct answer