Smoke is an uncountable noun and has no plural. You could speak in terms of puffs of smoke, or plumes of smoke.
Care
You could add the suffix -s to it to make the word isles.
falsehood
fragrance
It can be, if you add a suffix or prefix. For example, in the word 'going', 'go' is the base word, and '-ing' is the suffix.
To add a suffix to "habitat," you would simply attach the suffix to the end of the word. For example, adding the suffix "-ion" would create the word "habitation."
a
One suffix you can add is -en. In this case, the word would be seen.
To add the suffix '-ness' to 'immaterial', you would remove the last 'i' and add 'ness'. The word would become 'immaterialness'.
-ize
You would add the suffix -less meaning without or lacking, to make "senseless."
You can add the suffix "ment" to form the word "involvement."
The suffix that you would add to the root word truth in order to create a word that means by honesty is ful.
You could add the suffix -ed to it to make the word hunted.
Care
Legalizing
Sure, if you add the suffix "-ly" to the word "significant," it becomes "significantly."