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.

are alternate mass forms of an element. It has the same number of protons and electrons but differ in their number of neutrons

answer:   option a) glucagon was secreted by his pancreas before he ate the cookies because blood glucose was low. insulin was secreted after he ate the cookies because his blood glucose was high.

explanation:

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.