Which sentences describe the discipline of the natural science

Which of the following does not describe a physical property of iron? a iron is silvery-white or gray in color. b iron has a boiling point of about 3,000°c. c iron is a magnetic element . d iron and sulfur react to form iron sulfide.

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

When an object is moving away from you while still making a sound, the pitch of the sound is perceived to a. lower b. unchanged c. fluctuating d.higher