Interrogative adjectives are adjectives that are used in questions.
The interrogative adjective कैसा can be translated into English as “what kind of”, “what sort of”, or “how”. It inflects according to gender, number, and case. The masculine singular form is कैसा, the masculine plural form is कैसे, and the feminine singular and plural form is कैसी. In the oblique case, the masculine singular and plural oblique form is कैसे, and the other oblique forms are the same as the direct forms.
यह कैसी मूवी है – “What kind of movie is this?”
यह मूवी कैसी है – “How is this movie?”
Note the difference between the attributive and predicative usage – as an attributive adjective, कैसा means “what kind of”, but as a predicate adjective, is means “how”.
आप कैसे मकान में रहते हैं – “What kind of house do you live in?”
यह कैसा फल है – “What sort of fruit is this?”
The interrogative कौन with the particle सा forms an interrogative adjective that can be translated as “which” in English. The सा inflects like any adjective.
कौन सी मूवी देखनेवाली हो – “Which movie are you going to watch?”
कितना means “how much/how many”:
हम कितने लोग हैं – “How many people are we?”
आपके दफ्तर में कितने लोग काम करते हैं – “How many people work in your office?”
यहाँ कितनी किताबें हैं – “How many books are here?”