Answer:
Hey there!
1. They are soft and spongy because they are mostly made of air spaces.
2. The trachea, which is also called the windpipe, is a tube that connects the larynx to the bronchi of the lungs.
3. Breathing through nose is better, because it can allow for more oxygen to get to the tissues.
4. You can use something called limewater. It turns a milky color in the presence of carbon dioxide.
5. Smoking and air pollutions are big causes of breathing problems.
Let me know if this helps :)