Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

What demands an answer, but asks no questions

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?

If an electric train is travelling south, then which way is the smoke going?

What jumps when it walks and sits when it stands?

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

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?

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 don't get anymore wetter, no matter how much rain falls on me.

The more of this there is, the less you see. What is it?