5. Titin is the largest molecule. But it only has a few elements

4. Four is the largest valency an element can have. Carbon and Phosphorous have a valency of four.

3. Uranus and Nepture are mostly made of Ammonia. 

• Ammonia is stinky and poisonous
  
  

2. My body is made up of about [65]% Oxygen, [18]% Carbon and [10]% Hydrogren. 

• The Oxygen I breath and the Oxygen from the water makes up a large part of my body. My body has 70% water and 8/9th of water by weight is Oxygen.

• The bones in my body are made of Calcium. It makes up [2-3]% of my body
  
  

1. Acetic Acid (found in Vinegar) and Baking Soda mixed together will make Carbon di oxide bubble out of the glass. 

Bonus 0. Fun fact

0. Some elements have ZERO valency. Most of the noble gasses have 0. But some Noble gasses like Radon and Xenon have a valency of 0.