While handling a project, the landscaper is asked by the owner of the mansion that he wants four trees in front of his mansion that are exactly equidistant from each other.

How will he do it?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

What has hands, but can’t clap?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

What is red and smells like blue paint?

The more of this there is, the less you see. What is it?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

If 2 workers can complete painting 2 walls in exactly 2 hours.

How many workers would be needed to paint 18 walls in 6 hours?

What has a ring but no finger?

In the Chess Board picture below white army is arranged. You need to add a black army on the board such that no piece is under any threat.
Note: Army comprised of 1 king, 1 queen, 2 rooks, 2 bishops, 2 knights, and 8 pawns.