Answer:
The outermost shell of helium for example is filled with only two electrons. Hydrogen and lithium become stable by acquiring the electronic configuration of the nearest inert gas, which is helium. This is the duplet (or duet) rule.
Explanation:
A rock is a solid, inorganic, naturally-formed substance without a particular atomic structure or chemical composition. It is made up of two or more minerals aggregated together. Hope this answers the question. Have a nice day. Feel free to ask more questions.
<u>Answer:</u>
Carbon and silicon both are tetravalent elements as compared to germanium, tin, and lead which are divalent.
That's because Ge, tin, and Pb show inert pair effect and has a greater nuclear effective charge on the 's' electrons due to poor shielding effect. .That's why these elements are not able to share their valence electrons while carbon and silicon does and show "catenation" which is the ability to form long chain molecules.
Answer:
The oxidation number of an atom is the charge it appears to have when you count the electrons according to some arbitrary rules. The oxidation number of an atom depends on the other atoms in the substance.
Explanation:
For example, In KCl, the oxidation number of Cl is 0.
Answer: 2mg
Part per million is unit that equal to mg/kg of water or simply

. In this case, you asked how much NaCl needed and know the volume of water(100mL), concentration(20ppm or 20 mg/kg) and water density.
Then, the equation would be
concentration = NaCl weight/ water weight
20 x

mg= NaCl weight/ (100ml x 1g/ml)
NaCl weight= 20x

mg/kg x 100g
NaCl weight= 2000 x

g
NaCl weight= 2x

g = 2mg