Riddles 1

See if you can solve all of these riddles!

1. What is the only question you can't say 'Yes' to?

2. As I was going to St. Ives,

    I met a man with seven wives,

    Each wife had seven sacks,
    Each sack had seven cats,
    Each cat had seven kits:
    Kits, cats, sacks, and wives,
    How many were there going to St. Ives?

3. A thief enters a shop and threatens the clerk, forcing him to open the safe. The clerk says, "The code for the safe is different every day, and if you hurt me you'll never get the code". But the thief manages to guess the code on his own.

4. When you know not what I am, then I am something. But when you know what I am, then I am nothing.

5. During what month do people sleep the least?

6. I'm easy to get into, but it is hard to get out of me.

7. What always eats but is always hungry?

8. Throw it off the highest building, and I'll not break. But put me in the ocean, and I will. 

9. I'm as light as a feather yet the strongest man can't hold me for more than a minute.

10. Pronounced as one letter,

      And written with three

      Two letters there are,

      And only in me,

      I'm double, I'm single,

      I'm black blue and grey,

      I'm read from both sides,

      And the same either way. 

Put your answers in the comments!