If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

Who is that with a neck and no head, two arms and no hands? What is it?

There are 2 sand hourglasses.

The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?

The more it dries, the wetter it becomes. Can you tell what it is?

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

How can a man go eight days without sleep?

What brings you down but never up?

Eight of us go fourth, not back, to protect our king from an attack. What are we?

In a supermarket, there is an intelligent glass pane before a refrigerating unit. This glass pane allows cherries and apples through it but does not allow grapes and Orange to pass through it.

Can you identify the rule that the glass pane is following?