Density = Mass ÷ Volume. You get 2.466
If you have a concern about fluoride in your drinking water, you can get more information by contacting the local community water system and is denoted as option D.
<h3>What is Water?</h3>
This is referred to as a universal solvent and is usually colorless and used for various purposes such as drinking, washing etc.
Fluoride is added to water by the the community water system as it helkps to build strong teeth and cavities thereby preventing tooth decay. They know the concentration which is added to the water which is why they need to be contacted for more information.
Read more about Water here brainly.com/question/5060579
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Answer : The frequency of a photon of radiation is, 
Explanation : Given,
Wavelength of the radiation = 670.8 nm
First we have to convert wavelength form 'nm' to 'm'.
Conversion used : 
So, the wavelength of the radiation = 670.8 nm = 
Now we have to calculate the frequency of a photon of radiation.
Formula used : 
where,
= frequency of a photon of radiation
= wavelength of the radiation
c = speed of light = 
Now put all the given values in the above formula, we get the frequency of a photon of radiation.
Therefore, the frequency of a photon of radiation is,
