In the United States, cell phones are a very popular item. The nouns in this phrase would be "United States" and "cell phones" but would "item" be considered a noun also??

Answer 1

United States = noun
cell phones = noun
item = noun

Note: although "cell phone" is listed in the dictionary as a noun, some teachers may consider "cell" an adjective modifying the noun "phone."

Answer 2

Her favorite pastime is entertaining friends.