Hello everyone, This site is so beautiful. There's an overwhelming amount of information and resources. It is a future scientist's dream to come across this site. I have fully committed to my goals of going further in physics and I am taking it a step up today due to posting here. My knowledge is low, and I am taking my first General Chemistry class, but I wanted to come here and post some questions I am having over my first assignment of Summer School. It's some rather basic concepts, but I want to make sure I have them down before proceeding: 1) A certain compound, when released from its container, is completely dispersed into the environment. Is this compound more likely to be a solid, liquid, or gas? My answer: Gas. It seems logical that gas would disperse fully into the air. 2) Ethylene glycol is very poisonous. This fact is a: My Answer: Chemical and Extensive property 3) Classify scratching a steel surface as a physical or chemical change. ^^ This one threw me off for a while. I understand when steel tarnishes/rusts it is a chemical change, but my teacher told me this one was a physical change. My answer: Physical But I would think that scratching a steel surface adds heat to the environment (motion) and thus, causes a chemical reaction. Am I wrong to think this? 4) Classify heating liquid methane unti it boils as a physical or chemical change. My answer: Chemical I'm not too familiar with liquid methane... but I would imagine the addition of the heat forces a chemical change. 5) Do the following calculation reporting your answer with the correct number of significant figures: 67.8x9.8/100.04 *At first, I thought this problem was an error, because due to order of operations I think it should be read as 67.8 * (9.8/100.04). Am I correct in proceeding this way with order of operations? (First division, then multiplication) *EDIT: Ok, now I feel stupid. It's the same regardless. :| Okay, that is all for my first assignment. I know it's mainly basic concepts and ideas, but I would like to confirm my thoughts as I take a serious approach. I also want to get more familiar with this site. Thank you for any guidance.