Use the drop-down menus to determine whether the following barriers are physical, chemical, or biological. chemical
lysozyme

skin

phagocytes

Langerhans cells

acid and oil secretions

sneezing or coughing

What are the student's observations and inferences before he starts his investigation?

How do water’s relative densities as a solid and a liquid differ from that of most other substances? water’s solid and liquid forms have different densities, while most other substances have solid and liquid forms with similar densities. water’s solid and liquid forms have similar densities, while most other substances have solid and liquid forms with different densities. water’s liquid form is less dense than its solid form, while the opposite is true of most other substances. water’s solid form is less dense than its liquid form, while the opposite is true of most other substances.

What happens when two nitrogen atoms share electrons