Water Bottles

Question: Two men/women in absolutely identical conditions have two of the exact same water bottles (full of water). An hour passes, and the temperatures of the water inside the bottles are measured. The temperature of one of the bottles is noticeably higher than the temperature of the other. Assuming that the temperature of the setting they were in, as they were both the same, had to do with the change in temperature of the water, why are they different?

Question: What can be broken but never forgotten?

Question: People see through me, but none pass through without killing me. I can be anywhere, and can be seen double or single. What am I?

Question: Which thing that comes once in a year, twice in a week?

Question: You are trying to get your chicken, fox, and wheat to the barn. However, the barn is on the other side of the river. You are on a boat and can only transport one animal or wheat at a time. You must choose carefully not to leave the wrong two together, though. It's either the fox will eat the chicken or the chicken will eat the wheat. How do you take each thing across safely?

Question: During what month do people sleep the least?