Interrogative adjectives in Icelandic grammar are affixed to nouns to form questions. These adjectives, such as ‘Hversu’, ‘Hvað’, ‘Hver’, ‘Hvaða’, and ‘Hve’, are fundamental parts of formulating open-ended questions in Icelandic. They often precede a noun they modify and agree in number, gender, and case, similar to regular adjectives. These exercises aim to help learners understand and utilize these question words in various sentence structures successfully.