which of the following is a proper noun
newpaper
Conchita Alonso
River
skyscraper

Conchita Alonso definitely looks like a proper noun to me. River with its capital letter looks suspicious too.

If a pub was called "River", then "River" would be a proper noun. If the word "River" means river; i.e. a load of water rushing downhill, then it's a normal noun.

There is a lesson on nouns here.