We can only see things if they give off light but be we use other senses to gather information about things we cannot see.
Simple,
take a look at your periodic table, if you have it labeled look at the Halogen
Group, it includes: Flourine, Chlorine, Bromine, Iodine, and Astatine.
Now, a period on the periodic table is read from left to right, and goes
down the rows of the periodic table.
Go to Period 5, go all the way to the Halogens, what is there?
Iodine.
Thus, your answer.
Answer:
There are 
grams contained in all the seawater in the world.
Explanation:
At first let is determinate the total mass of seawater (
), measured in grams, in the world by definition of density and considering that mass is distributed uniformly:
Where:
- Density of seawater, measured in grams per liters.
- Volume of seawater, measured in liters.
If 
and 
, then:
The total mass of sodium chloride is determined by the following ratio:
Given that and 
, the total mass of sodium chloride in all the seawater in the world is:
There are grams contained in all the seawater in the world.
