Riddle: I am the center of gravity, hold a capital situation in Vienna, and as I am foremost in every victory, am allowed by all to be invaluable. Though I am invisible, I am clearly seen in the midst of a river. I could name three who are in love with me and have three associates in vice. It is vain that you seek me for I have long been in heaven yet even now lie embalmed in the grave. What am I?
Answer: The letter V.
Riddle: An old fashioned bike wheel has 21 spokes. How many spaces are between the spokes - 20, 21, or 22?
Answer: 21
Riddle: My tines be long, My tines be short, My tines end ere, My first report., What am I?
Answer: lightning
Riddle: Mr. Grumper grumbles about bad time-keeping trains like everybody else. On one particular morning he was justified, though. The train left on time for the one hour journey and it arrived 5 minutes late. However, Mr. Grumper's watch showed it to be 3 minutes early, so he adjusted his watch by putting it forward 3 minutes. His watch kept time during the day, and on the return journey in the evening the train started on time, according to his watch, and arrived on time, according to the station clock. If the train traveled 25 percent faster on the return journey than it did on the morning journey, was the station clock fast or slow, and by how much?
Answer: The station clock is 3 minutes fast. The morning journey took 65 minutes, and the evening journey therefore took 52 minutes, and the train arrived 57 minutes after it should have left, that is, 3 minutes early.
Riddle: What is it that when you take away the whole you still have some left over?
Answer: Wholesome.
Riddle: Forwards it's heavy, backwards it's not. What is it?
Answer: Ton.
Riddle: When a trick is revealed, this person feels naive; on April 1st, they’re easy to deceive. Who am I?
Answer: A fool. “Fool” is central to the holiday’s name and theme of being tricked.  
Riddle: Why should you always carry a watch when crossing a desert?
Answer: It has a spring in it
Riddle: Before Mount Everest was discovered, what was the highest mountain on Earth?
Answer: Mt. Everest.
Riddle: What is the longest word in the dictionary?
Answer: Smiles (there is a mile between the two S's)