Can you solve this picture maths equation?

How many letters are in the alphabet?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

While going to your grandmother's house, you counted Twenty houses on the right side. While returning back to your home, you counted Twenty houses on the left side.

How many houses are there between your home and your grandmother's home?

What demands an answer, but asks no questions

In an interview, a boy was asked an unusual question 'How two persons sitting with a table in between them can't see each other?' He was unable to reply. Can you?

I have an eye but still cannot see.

Who am I?

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

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?