Question

rivers →
article is used
article is not used

names of countries in the plural →
article is used
article is not used

continents →
article is used
article is not used

streets →
article is used
article is not used

relatives →
article is used
article is not used

musical instruments →
article is used
article is not used

towns →
article is used
article is not used

mountain ranges →
article is used
article is not used

names of countries in the singular →
article is used
article is not used

family names in the plural →
article is used
article is not used

Answer 1

1) rivers - да (the Nile, the Danube)
2) да - НЕКОТОРЫЕ архипелаги и объединения стран (the Canary Islands, the Philippines, the United States)
3) continents - нет
4) streets - нет
5) relatives - нет (если имеются в виду родственники)
6) musical instruments - да и нет, в зависимости от случая и контекста (Where is my guitar? / Miss Anna plays on the piano every Saturday);
7) towns - нет ;
8) mountain chains - да (the Andes, the Rockies);
9) countries in singular- нет (кроме the Netherlands, the Dominican Republic и любой другой республики);
8) family names in plural - да (The Tolstoys often come to visit us.);