Learn Finnish: Paloiko ruoka? - Did the food burn?

The base verb is palaa (to burn). To form the past tense, the final -a changes to an -o before adding the past tense marker -i. This gives us paloi (it burned), to which the question particle -ko is attached.

I'm currently learning about Type 2 verbs. Is palaa a Type 2 verb?

It is actually a Type 1 verb, appearing here as a helpful review! Unlike Type 2 verbs where you drop the first vowel of a diphthong (like juoda becoming join), palaa doesn't have a diphthong. Instead, it follows the Type 1 rule where an -a at the end of the stem often changes to -o before the past tense -i.

Why is the question particle -ko attached to the verb instead of using a separate question word like "did"?

Finnish doesn't use auxiliary verbs like "did" or "do" for yes/no questions. Instead, you take the word you are asking about, add the -ko or -kö suffix, and move it to the front of the sentence. Paloiko literally means "Burned [it]?".

Is there a difference between palaa and polttaa for the English word "burn"?