Find the next number in the sequence

1, 2, 6, 21, 88, __?

Most people think of me as money. But when they find me in the water, they won’t get any money out of me. What am I?

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

For an extra income, John decided to work at a Hotel for one hour daily. The manager offers him that they will pay him $11 after every 11 days.
However, John offered a different proposition to the manager. The offers stand as:
He will be paid just a penny on his first day.
Two pence will be paid on the second day,
Four pence will be paid on the third day.
And so on till the 11th day.

Should the Hotel manager accept his offer?

Look at the picture and find out which square is not linked with any of the other squares.

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

A man embarked on a questionnaire game. He kept asking the same question to whomever he found. The answer each time was different.

Can you guess what the question was?

If you say my name, I will no longer exist. What am I?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

A man dies of old age on his 25 birthday. How is this possible?