Adding the suffix -ful makes rest and adjective.
Example sentence:
We had a restful afternoon reading by the fireplace.
'Rest' can be a noun ('I need a rest') or a verb ('rest assured').
By adding a suffix, you can change a noun into an adjective. worth --> worthless fool --> foolish rest --> restive
Norway is a proper noun, not an adjective. It is the name of a country. It does not change.
Adjective forms of the noun and verb rest include the present and past participle of the verb (to rest) which are resting and rested. Related derivative adjectives include restful, restive, and restless.
The adjective form is enigmatic.
How pluse rate change at rest?
No. Restful is an adjective. The adverb would be "restfully."
Occasional
fame
indignation
catastrophic
Leisure is already in its adjective form. It does not change between noun and adjective, only between noun/adjective and adverb. "Please complete this at your leisure." = noun "My favorite leisure activity is golf." = adjective "He completed the task leisurely." = adverb