Photosynthesis and respiration are supported by the recycling of and a. nitrogen, oxygenb. water, nitrogenc. carbon, oxygend. oxygen, nitrogen

According to the big bang theory, after the "bang," the universe remained dark until about  300,000 yearsone billion yearsthree minutesthree billion years  later, when neutral atoms began to form.

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.

What best explains the inability for life to exist in earth early atmosphere