Note to self... पानी is a masculine noun, and therefore takes ठंडा not ठंडी.
does मुझे go with है or हँ?
It depends on the subject. मुझे uses the oblique case: it is not the subject of the sentence. In Hindi, the water "is being liked by you". The subject is the water. So, in this instance, you need to use है.
I don't seem to have any sound anymore in these kind of exercises - anybody any idea what's wrong?