This is actually really is. Notice how the protons + the neutrons equal the top number next to the element and the bottom one is the amount of protons.
So for Rn, it already gives you the protons and the atomic number (the top number), you just subtract them ---> 209-86= 123 neutrons.
I don't have a periodic table to look at, but for the next one just add the protons and the neutrons to get the atomic number (the atomic number will be under the element symbol) and look for it on the periodic table to find the element and so on.
I hope this helps ♥
Answer:
Correct answer is: "Cold Water"
Explanation:
EDGE 2020
Any element in group 18 has eight valence electrons (except for helium, which has a total of just two electrons). Examples include neon (Ne), argon (Ar), and krypton (Kr). if that’s what u mean
Answer: The concentration of hydrogen ion is 2.5 x 10∧-3.
Explanation:
It is well known that; pH + pOH = 14
∴ pH + 11.40 = 14
pH = 14 -11.40 = 2.60
Remember that,
pH = - Log [ H+ ]
2.60 = - log [H+]
To get the hydrogen ion concentration, we take the anti-log of 2.60.
[H+] = Antilog 2.60 = 2.5 x 10∧-3.