Understanding word order

Although one of my favorite topics is word order, I have a lot of problems understanding word order. Let's see:

Look at the sentences below:

1. هَذَا رَجُلٌ This is a man.
2. هَذِهِ بَطَّةٌ This is a duck.

Notice that the word هَذَا comes before رَجُلٌ and the word هَذِهِ comes before بَطَّةٌ? I guess it can be concluded that in nominal sentences like these, the pronoun must come before the noun and not the other way around.


Now look at these sentences:

1. مَنْ أَنْتَ؟ Who are you?
2. أَيْنَ الأَسَدُ؟ Where is the lion?
3. مَاذَا عَلَى الْمَكْتَبِ؟ What is on the table?

In sentences like these, the interrogative articles مَنْ, أَيْنَ, مَاذَا are at the beginning of the sentences. In sentence 3, the phrase عَلَى الْمَكْتَبِ is a prepositional phrase, thus the preposition عَلَى must come before the noun الْمَكْتَبِ.

Now look at this sentence:

1. حَقِيْبَةُ مَنْ هَذِهِ؟ Whose bag is this?

In this sentence I don't why the interrogative article مَنْ is not at the beginning but in the middle of the sentence. In other words, I don't know how to explain the word order of this sentence.