The difference between Indo-European and Common Germanic groups?

Smart people of Reddit, could you please help me with my homework? I don't need it done, could you just pls give a tip on how to prove that a word belongs to a certain group? What are the main features of each group? The task I'm talking about:

1. Define to what group (Indo-European or Common Germanic) the native words belong. How can you proof it? Define etymology of borrowed words.

 need, leg, young, mother, eye, fire, whiskey, wine, room, to do, to drink, to break, cotton, long, sharp, to know, wrong, guess, court, cognac, lobby, vermouth, algebra, to love, hunger, donor, verst, bravo, patio, dogma.