This is the 478th most frequent Lithuanian word.
klausimus
"klausimus" – "questions" (accusative plural form of "klausimas").
In this sentence, 'klausimų' is in the genitive plural form, used after 'daug' (many) to denote the quantity of questions.
Studentai uždavė daug klausimų mokytojui.
The students asked the teacher many questions.
'Klausimas' here is in the nominative singular form, as it is the subject of the sentence.
Praeitas klausimas buvo labai sunkus.
The previous question was very hard.
Here, 'klausimus' is in the accusative plural form, indicating the direct object of the phrase 'sukosi apie'.