Can you replace the question mark with the correct number in the below table sequence?

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?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

It is a 5 letter word if you take away first letter it is something you get from sun, if you remove second letter you will get something to eat, if you remove third letter you get a word you use in pointing at and if you remove the fourth letter you get something to drink. What is it?

You have three orange, two pink and five purple balls in the drawer beside your bed. There is no electricity and the room is entirely dark. How many balls must you take out to ensure at least one ball of each colour at least?

How can you take 2 from 5 and leave 4?

There is a certain crime, that if it is attempted, is punishable, but if it is committed, is not punishable. What is the crime?

Prove that the below maths equation is true.

8 + 8 = 91

Can you decipher the two rows to find the hidden word?

A man lives on the fifteenth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets into the elevator, and, if there is someone else in the elevator, or if it was raining that day, he goes back to his floor directly. Otherwise, he goes to the tenth floor and walks up five flights of stairs to his apartment. Can you explain why he does this?