Final answer:
The adjective in the sentence is 'nervous', and the adverb is 'skillfully'. Adjectives describe nouns, while adverbs modify verbs, adjectives, or other adverbs.
Step-by-step explanation:
In the sentence “Although she was nervous, Cecilia skillfully played the intricate violin solo,” the adjective is “nervous,” which describes the subject ‘Cecilia’ by indicating her state of mind. The adverb is “skillfully,” which modifies the verb ‘played’, describing how Cecilia played the violin solo. An adjective describes a noun, providing more information about it, while an adverb modifies a verb, an adjective, or another adverb, often indicating manner, place, time, frequency, degree, level of certainty, etc.