B. NaCl
All of the other answers contain a 2 or a number in general. Metals do not form covalent bonds. Alkali-halide salts are Ionic compounds. Ionic compounds form from bonding a metal and a non metal. Covalent bonds are formed by bonding non metals.
It is currently organised by the increasing atomic # based on the actual nuclear charge of the elements
Access to Alternative Source of Fuel.
Reduce Surface Toxicity.
Lower Energy Cost.
More Jobs.
Buys More Time.
Requires Huge Amounts of Water.
Possible Water Contamination.
May Trigger Earthquakes.
As you inhale, your ribs move up and out decreasing the internal pressure and increasing the volume of the lungs forcing air into the lungs from an area of externally high pressure in comparison to the low internal pressure.