Using Only Five 5's and any mathematical operator make sum as 37

What has 13 hearts but no other organs?

If you paint a brown house white it will become a white house. If the stoplight changes from red to green, then the light is green. So, if you throw a white shirt into the Red Sea, what will it become?

Manish has to secure 40% marks to pass his B.tech final exams.
He got just 40 marks and failed by 40-marks.

What is the maximum marks?

I am the fastest animal but cannot climb the tree. What am I?

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?

He runs but never walks. Murmurs, but never talks. Has a bed, but never sleeps. And has a mouth, but never eats?

An evil man kidnapped someone and made them take one of two pills. One was harmless, but the other was poisonous. Whichever pill the victim took, the kidnapper took the other one. The victim took their pill with water and died. The kidnapper survived. How did the kidnapper get the harmless pill?

No one wants to have it, but if one got it, he does not want to lose it. What is It?

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