Please choose the correct answer to the question: A teacher opens a can of food in the front of a classroom. Soon, all of the students in the classroom can smell the food. Which statement identifies a property of a gas that allows all of the students to smell the food?

Answer1: A gas has no mass. Answer2: A gas has a large mass. Answer3: A gas takes the shape of its container. Answer4: A gas keeps its shape when placed in a container.

Answer format: answer1/answer2/answer3/answer4