What is the atomic number for Sodium?

11

Explanation:

If you look at the periodic table, sodium's atomic number is 11, which means it has 11 protons in the nucleus.

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.