When I was correcting your paper exams, I realised you are still confused with WHOSE at questions. Let's see that again ...
WHOSE indicates POSSESSION, and like WHICH or WHAT can be used with or without a Noun as a question word. Now, let's focus on the following questions and answers, all of them are correct, possible in English, though they are slightly different.
1. Whose are these pencils?(correct) -
These pencils are mine; They are mine; These are my pencils, These are Helen's.(possible answers)
2. Whose pencils are these? (correct)
3. Whose are these? (correct)
Now, I hope to clear it up for you!!! ;)