Q. The energy required to break one mode of $Cl - Cl$ bonds in $Cl_{2}$ is 242kJ$mol^{- 1}$. The longest wavelength of light capable of breaking a single $Cl - Cl$ bond is
A) 594 nm
B) 640 nm
C) 700 nm
D) 494 nm
Explanation
(d)
Energy required for 1 $Cl_{2}$ molecule $= \frac{242 \times 10^{3}}{N_{A}}J$
$E = \frac{hc}{\lambda}$
$or\ \lambda = \frac{hc}{E} = \frac{6.626 \times 10^{- 34} \times 3 \times 10^{8} \times 6.02 \times 10^{23}}{242 \times 10^{3}}$
$= 494 \times 10^{- 9}m = 494\ nm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.