Which is the noble gas notation for chlorine?

[ne] 4s^2 4p^5
[ne] 3s^2 3p^5
[ne] 3s^2 3p^3
[ne] 3p^2 3p^5

What’s the percent by mass of carbon in c10h14n2

How are isotopes of the same chemical element alike? how are they different?

About 3% of the water on earth is freshest. only about 40% of that freshwater is available for human use. why is so much freshwater unavailable for human use?