VITEEE 2009 Paper

∵ 1‌mol=6.023×1023 atoms
KE of 1‌mol=6.023×104J
or KE of 6.023×1023 atoms = 6.023×104J
∴ KE of 1 atom =

6.023×104

6.023×1023

=1.0×10−19J
hvenergy=

hc

λ

=

6.626×10−34×3×108

600×10−9

=3.313×10−19J
Now since Threshold energy = hv - KE
=3.313×10−19−1.0×10−19=2.313×10−19J
Hence minimum amount of energy required to remove an electron from the metal ion will be 2.313×10−19J.