Question

The binding energy of electrons in a metal is 193 kJ mol${}^{-1}$. The threshold frequency of the metal is :

• A. 8.83 $\times$ 10${}^{14}$ s${}^{-1}$
• B. 4.83 $\times$ 10${}^{14}$ s${}^{-1}$
• C. 5.83 $\times$ 10${}^{14}$ s${}^{-1}$
• D. 6.83 $\times$ 10${}^{14}$ s${}^{-1}$

Answer 1

Answer: (B)

4.83 $\times$ 10${}^{14}$ s${}^{-1}$

E(binding energy per atom) = $\frac{193\times {10}^{3}Jmo{l}^{-1}}{6.023\times {10}^{23}mo{l}^{-1}}$= 3.20 $\times$ 10${}^{-19}$ J atom${}^{-1}$
Threshold frequency of the metal, v = $\frac{E}{h}$ = $\frac{3.20\times {10}^{-19}J}{6.626\times {10}^{-34}}Js$ = 4.83 $\times$ 10${}^{14}$ s${}^{-1}$