Transform the word THINK into BRAIN while changing only one letter at a time in a manner that each of the word in the process is a real word!!!

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?

What can you hold in your right hand, but never in your left hand?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

Can you name an animal whose killing cannot be performed without spilling your own blood?

John needs to purchase 100 chocolates from three different shops and he has exactly 100 rupees to do that which he must spend entirely. He must buy at least 1 Chocolate from each shop.

The first shop is selling each chocolate at 5 paise, the second is selling at 1 rupee and the third is selling at 5 rupees.

How many chocolates should he buy from each shop?

There are nine letters in the below-given diagram. You have to form a nine-letter word using these letters.

There were three women in all the swimming costumes!
One was happy and the other two were sad!
The happy one was crying and the sad ones were smiling.
Why was this?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?