Final answer:
The prefixes and root words of the underlined words in the sentences are 'un' and 'kind' for sentence (a), and 'im' and 'pure' for sentence (b).
Step-by-step explanation:
(a) The prefix of the word 'unkind' is 'un' and the root word is 'kind'.
(b) The prefix of the word 'impure' is 'im' and the root word is 'pure'.
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