What has many keys but can’t open a single lock?

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

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

Why 1729 is a magic number? Answer Logically.

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

You can find some missing letters in the picture. By placing two particular letters in the spaces, you can form a nine lettered word beginning from one of the corners and going clockwise direction to the middle. Can you find out the letters and the word?

There is a five-letter word which has 3 consonants(all are same) and 2 different vowels.
Also, something wrong is associated with the word.

Can you name it?

I can sizzle like bacon,
I am made with an egg,
I have plenty of backbone, but lack a good leg,
I peel layers like onions, but still remain whole,
I can be long, like a flagpole, yet fit in a hole.