What happened when the wheel was invented?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

I have one of the three numbers: 1, 2, or 3 in my mind. I speak only truth. You can ask me just one question for which I will only reply in yes or no or don't know. What question will you ask from me so that you are able to know the number?

What four weights can be used to balance from 1 to 30 pounds?

He runs but never walks. Murmurs, but never talks. Has a bed, but never sleeps. And has a mouth, but never eats?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

Which tank will fill first?

what does this below rebus represent identXQQQQQME

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?