Here is the story hope this can help​

Announcer: the suffix is -er and the word announce with the addition of the suffix -er is a noun.

Boastful: the suffix is -ful and the word boast with the addition of the suffix -ful is an adjective.

Misspeak: the prefix is mis- and the word speak with the addition of the prefix mis- is a verb, the prefix does not change the part of speech to which this word belongs.

Victorious: the suffix is -ious and the word victor with the addition of the suffix -ious is an adjective.

Uncommon: the prefix is un- and the word common with the addition of the prefix un- is an adjective, the prefix does not change the part of speech to which this word belongs to.

Explanation:

Suffixes are letters that we add after the root of a word (the main part of the word) to form new ones. The addition of the Suffix can change the category of a word. For example, if the root of a word is a noun when we add a suffix it turns into an adjective, like beauty and beautiful.

Prefixes are letters that we add before the root of a word, and as well as suffixes, they can modify the part of speech of a word.