What does below rebus means ?

Why do we preferably have round manhole covers and not square ones?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

What part of the chicken has the most feathers?

What do you call a fish without an eye?

John went to meet his friend Jacob, but when he was about to reach the main gate, John notices that Jacob had a mighty dog who was fastened to the tree. The chain is long enough that it allows the dog to reach the main gate.

How can the John reach the main gate?

In this image, you can see three almost identical Doraemon images. Can you spot the odd one out from them?

One night, a man runs away from home. He turns left and keeps running. After some time he turns left again and keeps running. Later, he turns left one more time and runs back home—but when he gets home, he finds a man in a mask. Who was the man in the mask?

I am a type of room you cannot enter or leave. Raised from the ground below, I could be poisonous or a delicious treat. What am I?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?