How is the moon similar to a dollar?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

A man hijacks an aeroplane transporting both passengers(8 of them) and valuable cargo. After taking the cargo, the man demands nine parachutes, puts one of them on, and jumps, leaving the other eight behind. Why did he want eight?

Which number should replace the question mark?

81 x 9 = 801. What must you do to make the this equation true?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

Find the next number in the following series:
6, 14, 26, 98, __?

There is an English word that can be used up to four times in a row without modifying the spelling and form a valid grammatical sentence.

Do you know what word is that?

Can you find the missing piece of the Porsche?