Until it is measured, not known. Yet how you miss it when it has gone. What is it?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

Identify The phrase in the picture.

What does this simple rebus mean?

A non-stop marathon is the shared favourite sport of three brothers.

*The oldest one is fat and short and trudges slowly on.
*The middle brother's tall and slim and keeps a steady pace.
*The youngest runs just like the wind, speeding through the race.

"He is young in years, we let him run!" the other two brothers explained, "'because though he is surely number one, he is second, in a way." Why is it?

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

John has played 50 ODI's and his average is 50. How many runs should he score in his 51st ODI, so that his average score jumps to 51?

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.