What does this simple rebus mean?

Which of the below owl is odd one out?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

What does this say?

XLR8

You can win me and lose me but never buy me
You can not eat me and never want to part with me
I can make you cry or bring you joy
I am not a machine and definitely not a toy
You keep me but i am not forever just yours
You might find me in a case or on a shelf next to a vase
I am hard and i am tall if you bump me i am sure to fall
I am made of different materials and am at many events
If your lucky and fight hard I might be yours
What am I ?

In a concert, Christina is performing a dance show with her group.
At 10:00, she and her crew were dancing in an absolutely straight line. At that time Christina was standing in 4th position from both the front and back end of the row.

What was the size of her crew?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

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

By including only four matchsticks in below picture, you have to make "Four Triangles And Two Squares"

What is the centre of gravity?