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.

Which is faster, Heat or Cold ? Explain.

When we see 2 but call 10?

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

No matter how little or how much you use me, you change me every month. What am I?

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

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

A boy was at a carnival and went to a booth where a man said to the boy, "If I write your exact weight on this piece of paper then you have to give me $50, but if I cannot, I will pay you $50." The boy looked around and saw no scale so he agrees, thinking no matter what the carny writes he'll just say he weighs more or less. In the end the boy ended up paying the man $50. How did the man win the bet?

What occurs twice in a week, once in a year but never in a day?