Spot what is wrong here in below Picture?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

Teacher ask the student

'Why are you standing on that chair in music class ?'.

what did student replied ?

In a chess board, the queen piece can move horizontally, vertically and diagonally freely. The picture represents the same.Can you place 8 queens on the board in a manner that none of the queens can attack each other?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

Jigsaw captured 100 people and make them stand in a circle and all these people are labelled as Person1, Person2, Person3... Person100. He made them play a crazy game in which Person 1 shot Person 2 and pass the gun to the next person and so on until one stands alive.

Which person will survive in the end?

What happened when the wheel was invented?

Rahul decided to meet Simran so he boards a local train from Bombay station. Just after the station, there is a 1km long tunnel. The train starts and is now accelerating. Rahul is a claustrophobic guy, so what is the best position for him to sit?

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?