What does the below rebus riddle means?

I am eight letters long - "12345678"
My 1234 is an atmospheric condition.
My 34567 supports a plant.
My 4567 is too appropriate.
My 45 is a friendly thank-you.
My 678 is a man's name.

What word am I?

What number divided by 4 is the same as that number minus 4?

What you cannot hold but it is yours?

A sundial has the fewest moving parts of any timepiece. Which has the most?

Replace the question mark with the correct number in below Picture:

When monkey rotate the gear, which mark will be hit 1 or 2 ?

100 prisoners are stuck in the prison in solitary cells. The warden of the prison got bored one day and offered them a challenge. He will put one prisoner per day, selected at random (a prisoner can be selected more than once), into a special room with a light bulb and a switch which controls the bulb. No other prisoners can see or control the light bulb. The prisoner in the special room can either turn on the bulb, turn off the bulb or do nothing. On any day, the prisoners can stop this process and say "Every prisoner has been in the special room at least once". If that happens to be true, all the prisoners will be set free. If it is false, then all the prisoners will be executed. The prisoners are given some time to discuss and figure out a solution. How do they ensure they all go free?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

I am the fastest animal but cannot climb the tree. What am I?