The best quality answer I would say that it is cC
The chemical reaction in which number of atoms of each element present in the reactant side is equal to the number of atoms of that element in product side, such reactions are said to be a balanced chemical reaction.
The chemical symbol for sodium is
.
The chemical symbol for fluorine gas is
.
The chemical symbol for sodium fluoride is 
The sodium fluoride is prepared from the reaction between sodium metal and fluorine gas can be written as:

The above reaction is not balanced as the number of fluorine atoms are not same on reactant and product side. So, in order to balance the reaction we will multiply
with 2 on reactant side and
with 2 on product side. Thus, the balanced reaction will be:

Thus, the balanced chemical equation is
.
Answer:
Explanation:
Electrons are transferred from atoms of sodium to atoms of phosophorus. This transfer makes the sodium atoms positive and the phosphorus atoms negative. As a result, the sodium and phosphorus atoms strongly attract each other.
Answer:
Explanation:
Groundwater is stored in the open spaces within rocks and within unconsolidated sediments. Rocks and sediments near the surface are under less pressure than those at significant depth and therefore tend to have more open space. For this reason, and because it’s expensive to drill deep wells, most of the groundwater that is accessed by individual users is within the first 100 m of the surface. Some municipal, agricultural, and industrial groundwater users get their water from greater depth, but deeper groundwater tends to be of lower quality than shallow groundwater, so there is a limit as to how deep we can go.