How much it has to drop and how heavy it is. Hope this is what you're looking for:)
solution:
You need to find the frequency, and they have already given you the wavelength. And since you already know the speed of light, you can use formula (2) to answer this problem. Remember to convert the nano meters to meters because the speed of light is in meters. 
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Coal can replace petroleum base fuel when you are just heating something that dont need big amount of heat. examples of it is when producing steam, coal is just used to heat water and produce steam because coal is much cheaper and the coal can already do the job in heating the water
Answer:
NO2 is the molecular formula of nitrogen Oxide
Explanation:
Correct question
An oxide of nitrogen contain its own volume of nitrogen
its vapour dentity is 23. Find the molecular formula
Of nitrogen Oxide
Solution
As we know
Molecular Weight is equal to two times the vapour density
Hence, the molecular weight of Oxide of nitrogen is 2 * 22 = 44
Molecular weight of Oxide of nitrogen is the sum of atomic weight of nitrogen and oxygen
Molecular weight of Oxide of nitrogen = 14 + 16 *Y
14 + 16 *Y = 46
Y = 2
Hence, the formula is NO2
