Answer: Some challenges that I could see would be the walls, possibly a moat, tar, and the towers.
Explanation: The wall is obliviously a main problem, trying to get over it or through it is a difficult challenge. The moat (if it has one) means that there is more than likely only one way to get in or out. If it does have tar it means that the attackers are going to be put in a "sticky situation" And finally the towers, they have people at the top shooting arrows down at you, or throwing things at you.
Answer: Addition polymerization & Condensation polymerization
The answer is B. On a sunny day, the air over a lake will be cooler than the air over the bordering land.
How many atoms are in something determines it "mass"
