Spot what is wrong here in below Picture?

What goes through cities and fields, but never moves?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

Three men in a cafe order a meal the total cost of which is $15. They each contribute $5. The waiter takes the money to the chef who recognises the three as friends and asks the waiter to return $5 to the men.

The waiter is not only poor at mathematics but dishonest and instead of going to the trouble of splitting the $5 between the three he simply gives them $1 each and pockets the remaining $2 for himself.

Now, each of the men effectively paid $4, the total paid is therefore $12. Add the $2 in the waiters pocket and this comes to $14. Where has the other $1 gone from the original $15?

The answer I give is yes, but what I mean is no. What was the question?

A rubber ball keeps on bouncing back to 2/3 of the height from which it is dropped. Can you calculate the fraction of its original height that the ball will bounce after it is dropped and it has bounced four times without any hindrance ?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

Andrew sees a very rare bird named "Ruppell's vulture". Soon Andrew was dead. Can you explain the mystery, Mr. Sherlock?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

Which Number is the odd one out?

A) 7145
B) 2716
C) 5321
D) 4135