Wavelength of quantum of radiation is 620 nm. Number of quanta present in 10 joules is equal to 31.25×10x. Value of ‘x’ is equal to

Energy of one quanta(in eV/atom)=1240λ(in nm); Energy of one quanta(in ev/atom)=1240620=2 eV/atom;                                  Total energy(E)=Nhν;(hν= Energy of one quanta)                       Number of quanta(N)=T.Ehν=10J2×1.602×10-19J=31.25×1018