What number should come in place of the question mark below?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

One night, a woman receives a call from the police. They tell her that her husband was murdered and that she should come to the crime scene as soon as possible. The woman drops the phone, shocked, and drives 20 minutes to the crime scene. As soon as she reaches the crime scene, the police arrest her and she is convicted of murder. How do the police know she committed the crime?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

Doctor Alex and a bus driver John are both in love with the same woman named Olivia. The bus driver need to go for a long trip of 10 days, Before he left he gave Olivia 10 apples.

There was a blind man. He had four socks in his drawer either black or white. He opened it and took out two socks. Now the probability that it was a pair of white socks is 1/2.

Can you find out the probability that he had taken out a pair of black socks ?

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?

What is the below Rebus indicate?

Can you identify the hidden rebus in the image below?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?