I am white when I am dirty, and black when I am clean. What am I?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

Can you find out the next digit in the following series ?

0, 0, 1, 3, 2, 6, 3, 9, 4, 12, 5, ?

When you stop to look, you can always see me. But if you try to touch me, you can never feel me. Although you walk towards me, I remain the same distance from you. What am I?

I have two sand hourglasses:
1. A 7 minute one and
2. An 11-minute one.

Using just these 2 sand hourglasses, how can I measure time as 15 minutes?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

Two prisoners Jack and Jill are locked in a cell.
There is open window approx 40 feet above the ground of the cell.
They are never able to reach there.

Then they plan to escape by a tunnel and they start digging out.
After digging for more than 20 days, Jill comes with the different plan and they escaped.

what was the plan ?

French Police inspects a room where there are no windows, no doors, no tables and is almost empty expect there is just a puddle of water. They found a dead man who obviously hung herself from the ceiling, but they are not able to figure out how this had happened.

John and Jacob entered the crime scene and easily able to solve the case.

How did the man die?

What number replaces the question mark

Highly detail-oriented individuals excel at this type of optical illusion challenge. It requires not just good eyesight but also the ability to distinguish subtle differences quickly. Finding the 6 among all these 9's could indicate a high level of IQ and superior observational skills.