De Broglie wavelength λ=hp and kinetic energy, K=p22m
Thus, KAKB=P2AP2B=λ2Bλ2A=4 as λB=2λA
Given, KB=(KA−1.5)=4KB−1.5⇒KB=0.5eV
Thus, KA=4×0.5=2.00eV
From photo-electric effect:
Work function of A =4.25−KA=4.25−2.00=2.25eV
and work function of B =4.70−KB=4.70−0.5=4.20eV
Thus, only the option D is wrong.