What has many keys but can’t open a single lock?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

What number comes next in the series?

5 15 5 18 5 24 14 20 _

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

A farmer and his neighbour once went to Emperor Akbar"s court with a complaint. "Your Majesty, I bought a well from him," said the farmer pointing to his neighbour, "and now he wants me to pay for the water."
"That"s right, your Majesty," said the neighbour. "I sold him the well but not the water!"?
The Emperor asked Birbal to settle the dispute. How did Birbal solve the dispute?

John is the son of Jacob.
So,
Jacob is the_____of John's father?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

What number do you get when you multiply all of the numbers on a telephone's number pad?

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

Find three numbers such that

* When we multiply three numbers, we will get the prime numbers.
* The difference between the second and the first number is equal to the third and second.