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

What is the word or phrase?

Sharpen your observation skills as you compare two seemingly identical images. Grab a magnifying glass, involve a buddy, and unleash your inner detective. Check the solution to see if you're a difference-detecting maestro!

What do you think with the below Picture ?

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.

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Do you know of a place where the wind blows south and then suddenly shifts direction towards the north?

What have one eye but still cannot see?

A wealthy man lives alone in a small cottage. Being partially handicapped he had everything delivered to his cottage. The mailman was delivering a letter one Thursday when he noticed that the front door was ajar. Through the opening he could see the man's body lying in a pool of dried blood. When a police officer arrived he surveyed the scene. On the porch were two bottles of warm milk, Monday's newspaper, a catalog, flyers, and unopened mail. The police officer suspects it was foul play. Who does he suspect and why?

Two guards were guarding the camp.Guard-1 was looking towards the south to make sure no threat is coming from the road.Guard-2 was looking at the north to make sure no threat is coming from the top. Suddenly Guard-1 ask the Guard-2 why he is smiling?How Guard-1 knows that Guard-2 is smiling?