Can のreplace ですか when asking a question?

Question

I recently encountered a situation when のwas used and want to know if either of the terms can be used interchangeably. Thank you.

Answer 1

Not exactly replace.

の particle can be used for questions or answers, it means that you're either seeking explanation or explaining something.

The only grammar rule here is that if it is preceded by a NA-Adjective or a Noun you need to add な before the の.

For instance:

どこ行くの？(doko iku no?) - Where are you going?(seeking explanation) - Informal.

どこに行くのですか？(doko　ni iku no desu ka?) - Where are you going (seeking explanation) Formal.

どこ行くのか？(doko iku no ka?) - Where are you going (seeking explanation) informal but the か gives more emphasis to your question.

I often see people saying that ending answers and questions with の　may sound a bit feminine, so in order to avoid it you should end your sentence with だ、です、ですか, depending if it's an answer or question.

Also you could abbreviate の　to ん.

どんな車好きなんだ？(don'na kuruma suki nanda?) - What kind of car do you like? (seeking explanation) Informal.

速い車好きなんだよ！(hayai kuruma suiki nanda yo!) - I like fast cars! (Explaining) informal.

何をしてるんですか？(nani wo shiterun desuka?) - What re you doing?(seeking explanation) somewhat formal.