You can have a solution of hydrogen peroxide that might say 10% that means that 10% per mass of the hydrogen peroxide solution is the hydrogen peroxide the rest is water.
concentration is the amount of mass in the solution eg 5gdm-3
hope that helps
There are only 2 atoms in an Oxygen molecule
This is a incomplete question. The complete question is:
It takes 348 kJ/mol to break a carbon-carbon single bond. Calculate the maximum wavelength of light for which a carbon-carbon single bond could be broken by absorbing a single photon. Round your answer to correct number of significant digits
Answer: 344 nm
Explanation:
E= energy = 348kJ= 348000 J (1kJ=1000J)
N = avogadro's number = 
h = Planck's constant = 
c = speed of light = 

Thus the maximum wavelength of light for which a carbon-carbon single bond could be broken by absorbing a single photon is 344 nm
Let's understand the situation
You are using an oil based paint .We know oil contains hydrocarbons means CH- bonded compound . Hydrocarbons are known as organic compounds and non polar .The thing non polar doesn't matter much but thing organic matters .
Now coming to water ,water contains OH bonding ,a lone pair is present over O which makes water polar . Although water is also known as inorganic compound.
We know that like dissolves like .In that manner Organic compounds are soluble in only organic compounds and not in inorganic compounds like water .Thus oil paint is insoluble in water as particles don't dissolve
Hence to clean the oil you need organic solvents like toulenw,spirit ,Benzyl compounds etc .