Listed alphabetically by last name, which U.S. president comes last?

Alpaca wool was a major commodity in which South American empire that expanded greatly in the 1400s? Alpha Centauri lies about 4.4 of which units away from us? Which magazine did John H. Johnson found in 1951, six years after he founded Ebony? Listed alphabetically by first name, which U.S. president comes last? Which continent's countries run alphabetically from Argentina to Venezuela? Alphabetically, which of Snow White's seven dwarfs comes first? Listed alphabetically by last name, which U.S. vice president comes first? Alphabetically, which noble gas comes last?