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.

It's a 7-letter word.
If we remove 1 letter from it, it remains the same.
If we remove 2 letters from it, it remains the same.
If we remove 3 letters from it, it remains the same.
If we remove all the letters from it, still it remains the same.
What is it?

How can you drop a raw egg from a height onto a concrete floor without cracking it?

With the help clues provided in the image, can you find the 5 digit key?

They are three errirs in this question. Can you find them?

We have four gears with below features=> Both Gear A and D has 60 teeth=> Gear B has 40 teeth=> Gear C has 20 teeth=> Every two minutes, Gear B makes 25 full turns.What is the relative speed of Gear A and Gear B?

How can you take 2 from 5 and leave 4?

Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation. Conditions: Each must be used exactly once and no other numbers or symbols can be used.

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

Eight of us go fourth, not back, to protect our king from an attack. What are we?