Is it a purple ruler?
Yes, it is a purple ruler.
Is it a blue pen?
Yes, it is a blue pen.
Is it a red pen?
No, it isn't a red pen.
Is it a green pencil?
No, it isn't a green pencil.
Is it a black door?
No, it isn't a black door.
Is it a yellow book?
No, it isn't a yellow book.