Explain how the isotopes of an element differ.

a. they each have a different number of electrons in their outermost energy level.
b. they each have a different number of protons in their nuclei.
c. they each have a different number of neutrons in their nuclei.
d. they each have a different charge.

An example of internal feedback working to maintain homeostasis is your a. decreased respiration rate when you are studying b. decreased heart rate when you are sad c. increased respiration rate when your muscles need more oxygen d. increased heart rate when your lungs need more oxygen

In which state was more than 100 billion tons of coal mined in 2005?

The embryos of a bird, a reptile, and a mammal are similar in appearance. how does comparing the physical appearance of embryos of different species support the theory of evolution? a. it shows that these organisms share a common ancestor. b. it provides evidence that these organisms eat the same foods.c. it shows that these organisms share the same habitat.d. it provides evidence that these organisms suffered a genetic mutation.