Can someone plz help I post a question before this one plz check it out I fr need help

Iron reacts with oxygen to produce iron oxide (rust). this reaction is represented in an equation as 4fe + xo2 → 2fe2o3. identify the value of x that will balance the equation.

Study this image which statement best describes the rock shown check all that apply

Which of these substances does not protect against invaders in the nonspecific immune response? a. saliva b. mucus c. tears d. urine