Какой vs что - when asking questions

Question

If I wanted to ask someone, "What sport do you like?" or almost the same thing, "Which sport do you like?" - this latter being used as if a parent was asking a child while they were reviewing a sign-up sheet for try-outs at school what sport they may like.

Are these two cases best translated by,

Что спорт ты любишь? Какой спопт ты любишь?

Or is the first one always improper?

Answer 1

The first one will be incorrect using of the word, at least with that punctuation and words order (and the meaning). You could use it in this combination:

Что, ты спорт любишь ?

However it changes meaning quite a bit and becomes more like "Well, it appears that you like sport ?". Word "что" will become as particle for increasing effect of the question.

To ask for clarification according to your examples you will use:

Какой спорт ты любишь ?

Another way, more of formal language, but still acceptable would be:

Что за спорт ты любишь ?

In general, you'll use "что" when asking about thing / fact / anything described with a noun, while "какой" - for description of that noun.

- Что ты любишь читать ?  
- Художественную литературу.
- А какой жанр ты предпочитаешь ? (Что за could  be also used here)

Answer 2

You are right, only "Какой спорт" is correct.

In general, "Что" in questions of such kind requires a dependent verb, which, however, could often be "is" (есть), which, as you know, is usually implicit in Russian.

Что полезного производит спорт? Что такое спорт? (= Что есть спорт?)

When you are asking to qualify or select one of a class, like in your example, you always need to use words какой or который. These two words approximately account for the subtle difference between what and which in your example: какой usually qualifies from a generic set of unspecified/unknown alternatives (какой цвет тебе больше нравится?), while который assumes a known set: который из этих цветов ты выберешь? However, какой is more generic and can usually be used for both cases.