Boomers: How Many of these science myths do you know?

Baby boomers are all old enough to have heard every possible science myth. Of course, not everything we've heard over the years is true. How many of these factoids have you heard, which ones are true, and which ones are urban legends?

1. Chickens can live without a head
2. Water drains backwards in the Southern Hemisphere due to the Earth's rotation
3. There is no gravity in space
4. Humans use only 10 percent of their brains
5. Eating a poppy seed bagel mimics opium use
6. A penny dropped from the top of a tall building could kill a pedestrian
7. Adults don't grow new brain cells
8. Chicken soup can cure the common cold
9. Yawning is "contagious"
10. Lightning never strikes the same place twice
11. A dog's mouth is cleaner than a human's
12. Hair and fingernails continue growing after death
13. A falling cat will always land on its feet
14. Men think about women every seven seconds
15. You get less wet by running in the rain
16. The five second rule
17. Animals can predict natural disasters
18. Seasons are caused by the Earth's proximity to the sun
19. The Great Wall of China is the only manmade structure visible from space
20. It takes seven years to digest gum

Answers here.