Cecil writes the equation for the reaction of hydrogen and oxygen below. H2 + O2 → H2O

Why does his teacher ask him to balance the equation by including the correct coefficients?

to show that most molecules exist in pairs
to show that most compounds exist in pairs
to show that atoms are conserved in chemical reactions
to show that atoms are created in chemical reactions

Snakes, dogs, and humans have a vertebral column. snakes and dogs have tails, and humans have vestigial tailbones. dogs and humans have limbs, but snakes do not. most reptiles lay eggs, but a few give birth to live young. what do these structures suggest about the evolutionary pattern between the three organisms? 1. snakes and dogs are more closely related than snakes and humans. 2. snakes and humans are more closely related than humans and dogs. 3. dogs and humans are more closely related than snakes and humans. 4. dogs, snakes, and humans share a common ancestor. 5. the early ancestor of snakes and dogs is the same, and the early ancestor of humans is different.

Which group of college students is typically offered scholarship? a. freshmen, sophomores, and juniors. b. biology, english, and engineering majors. c. hard workers, part-time students, and out of state students. d. first time freshmen, current students, and transfer students.

If you are in grade when should you start studying for exams