What is both possible and impossible at the same time?

Find the hidden panda in the image below.

The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

What number should come in place of the question mark below?

Through your logical capabilities, can you make 7 an even?

Using mathematical symbols like +, -, and x in order to make the equations correct. Replace # with the above-given symbols.

9 # 8 # 7 # 6 # 5 # 4 = 91

You need to remove two matchsticks to make the below equation true. Can you do it ?

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.

Can you make four (4) nines (9) equal 100?