Which gas was not present around the time earth first formed?

methane
hydrogen
oxygen
nitrogen

Which of the following is not a characteristic of carnosaurs? a. long narrow skulls b. strong forelimbs c. horn projecting from their skulls d. none of the above

The pharynx is the structure in the body that serves as a pathway of both air and food. how does the body make sure that food does not get into the lungs? the salivary glands secrete enzymes that pull food out of the air pathway. the small intestine pushes the air out of the digestive system. the pancreas breaks down food in the air pathway. the epiglottis closes the air pathway so that food will not enter it.

Draw the structure of dna nucleotide with adenine as nitrogenous base