Solid and liquids are much more denser than gas because their molecules are close to each other and with that the molecules of them can't move that freely unlike the gas molecules. Also, because of being near to each other the molecules of solid and liquids became heavy making them dense.
        
             
        
        
        
The reason why icebergs float in the ocean has to do with temperature. Icebergs are colder than the ocean water and therefore the cold water is less dense than the warm water and this causes the Iceberg to float.
        
             
        
        
        
Answer: 430 nm.
Explanation:
The relation of wavelength and frequency is:
Formula used : 
where,
 
 = frequency =
 = wavelength  = ? 
c = speed of light = 
Now put all the given values in this formula, we get
        
Thus the wavelength (in nm) of the blue light emitted by a mercury lamp is 430 nm.