Learn Turkish: Neresi daha kalabalık? Giyim mi, elektronik mi? - Which place is more crowded? Clothing or electronics?

Neresi is the subject of the sentence, meaning 'which place.' You use it when asking for the identity of the place itself. If you used Nerede, you would be asking 'where is it more crowded?' (referring to a location where an event happens), rather than asking 'which specific area is the crowded one?'

Could I use Hangi (which) instead of Neresi?

Yes, you could say Hangi bölüm (Which department). However, using Neresi is a very natural and common way in Turkish to ask 'which part' or 'what area' without needing to add a noun like 'department' or 'floor.'

Why are there two mi question particles in the second part?

When asking an 'either/or' question in Turkish, it is very common to put the question particle after both options. Giyim mi, elektronik mi? literally translates closer to 'Is it clothing, or is it electronics?'

How does giyim mean the physical place? Doesn't it just mean 'clothing'?

Context is everything! In a store or shopping mall, category names like giyim (clothing) or elektronik (electronics) are used directly to mean the departments or sections. The word Neresi in the first sentence sets up the context that we are talking about physical areas.