Learn Arabic (Modern Standard): أي قطن استخدم المصنع؟

When أي (which) asks about a singular noun, it forms an Idafa (possessive construction) with the noun that follows it. In Arabic, this following noun must be indefinite. You say أي قطن (which cotton) rather than using the definite article.

Does أي change its vowel endings depending on the sentence?

Yes! Unlike most question words in Arabic, أي changes its case ending depending on its role. Here, it is the direct object of the verb استخدم (used), so it takes the accusative case with a fat-ha on the end, making it أيَّ.

Why is the subject المصنع (the factory) placed at the very end of the sentence?

This sentence follows standard Arabic word order. Question words must come first, so the object أي قطن leads the sentence. After that, Arabic prefers to put the verb استخدم before the subject المصنع.

I recognize the letters خ د م in the verb استخدم. Is it related to the word for service?

Exactly! The root خ د م relates to serving. Adding the prefix استـ to a root often creates a verb meaning to seek, use, or utilize something. So استخدم literally means to put something into service, or simply to use.