"Whose parents eat dinner?"
Translation:Czyi rodzice jedzą kolację?
Yes and kind of no. Czyi is the masculine personal plural (ie. including at least one masculine person) form, usually pronounced /ˈʧɨ.ji/, two syllables. Czyj is masculine singular form, pronounced /ʧɨj/, one syllable.
Kind of, because in fast speech czyi can be shortened to /ʧɨj/, but not in slow, careful one.
Why wouldn't you use Obiad for the correct one (mid-day meal) and Kolacja for the correct one (evening meal)? I don't know why it is a problem. If you ask in English, I would say Lunch and Dinner, as the vast majority of people use it this way, and I am still skeptical of this so-called British idea of calling lunch dinner.
No need for scepticism! http://dictionary.cambridge.org/dictionary/english/dinner
To my knowledge it's only regional (including my region) and idiomatic.