Stars are just as often thought of as yellow or gold. There are also blue and red stars.
In all other exercises in this quiz they are using the article "The" for sun, moon , stars etc. However when i said "the stars are white", i was marked wrong and "Stars are white" was suggested as the right answer. I think both should be acceptable.
Not quite. होते here implies that we are talking about stars in general, and not a specific group of stars. तारे सफ़ेद हैं would be THE stars are white.