Energy is calculated by molecule dividing energy by mole by Avogadro's number (6.022*10^23)
 
 
 
 941kJ=9.41*10^5 J
 
 
 
 so energy by molecule 
 
 E= 9.41*10^5/6.022*10^23=1.563*10^-18 J
 
 
 
 Wavelength (w) given by E=hc/w
 
 where, E = energy
 
  h = planks constant (6.6262 x 10-34 J·s)
 
  c = speed of light (3 x 10^8 m/s )
 
 So,
 
  w= hc/E
 
  = (6.6262*10^-34)*(3*10^8) /1.563*10^-18
 
  = 127.2 Nm
 
 Longest wavelength of radiation =127.2 Nm