5º: Unit 3: Countable and uncountable nouns, how many, how much...

 Countable and uncountable nouns:

https://agendaweb.org/exercises/grammar/countable-uncountable/test-1

https://agendaweb.org/exercises/grammar/countable-uncountable/test-2

https://test-english.com/grammar-points/a1/a-some-any-countable-uncountable/ (there are 3 exercises)

https://www.examenglish.com/grammar/A2_Uncountable_nouns.htm

How much and how many:

https://www.englisch-hilfen.de/en/exercises/confusing_words/much_many3.htm

https://agendaweb.org/exercises/grammar/countable-uncountable/how-much-how-many-test-1

https://www.englisch-hilfen.de/en/exercises/confusing_words/much_many4.htm

https://www.english-4u.de/en/grammar-exercises/how-much-many.htm

much, many, little, few, some, any:

https://test-english.com/grammar-points/a2/much-many-little-few-some-any/ (there are 5 exercises)