Question

Fill in the blank with the correct indefinite article - un, una, unos, unas.

Answer 1

Unos - alumnos
Una - clase
Unas - amigas
Un - amigo

Answer 2

First one is unos because it’s male and plural.
Second is una I think. If you can use things multiple times might want to check again.
Amigas is unas since it’s plural and female
The last one is uno since it’s male and singular