A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?

Find the missing number in the sequence below:

Divide 110 into two parts so that one will be 150 per cent of the other. What are the 2 numbers?

What is always in front of you but can’t be seen?

Count the number of balls in picture below:

A person was killed at a house party. When the police arrive, there are six people present in the house who are the friends of the victim. The name of the friends is Rohit, Aman, Nick, Gagan, and Randy.

Near the dead body, they find a few numbers written with blood by the victim on the floor. The numbers are 8, 5, 4, and 11.

The police arrests one of the friends for the murder. Whom did they arrest and why?

Dwayne Johnson was running away with the loot from a heist in his car along with Vin Diesel. One tire was punctured and he dropped down to replace it. While changing the wheel, he dropped the four nuts that were holding the wheel and they fell into a drain. Vin Diesel gave him an idea using which they were able to drive till the rendezvous point.

What was the idea ?

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