Molarity is a measure of a solution's concentration calculation by getting the ratio of the number of moles of solute to the total volume of solution. This has a unit of M or molar, equivalent to mole/L. 
It is more important and meaningful to know the molarity rather than if the solution is dilute or concentrated because molarity gives the QUANTITATIVE approach of knowing the concentration while the second one only gives us the QUALITATIVE description of the solution. Hence, we are able to calculate for other unknown parameters if we have the molarity known.
        
             
        
        
        
Reactivity of Group 1 and 2 elements increases as you go down the periodic table. So sodium is more reactive than lithium. Sodium will react with oxygen forming Na2O (sodium oxide). Lithium forms lithium oxide (Li2O).
        
             
        
        
        
The answer you are looking for is True
        
             
        
        
        
When a gas bubbles through water, small droplets of water are usually picked up along for the ride and are mixed in with the gas above the water inside the eudiometer tube. The water vapor takes up room, but isn't the important gas that you need to measure. The table of water vapor is needed to subtract the unwanted water vapor from the collection of gases.