The atomic mass of Europium is 152 amu
Work:
151(0.4803) = 72.52 amu
153(0.5197) = 79.5 amu
72.5 + 79.5 = 152 amu
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
Because a good stepping stone would be a solid and if that solid were to melt or turn to gas you’d have no stepping stone.