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The work function () of some metals is listed below. The number of metals which will show photoelectAtomic Structure Chemistry Question

Question

The work function ($\phi$) of some metals is listed below. The number of metals which will show photoelectric effect when light of 300 nm wavelength falls on the metal is<br><br>\| Metal \| Li \| Na \| K \| Mg \| Cu \| Ag \| Fe \| Pt \| W \|<br>\| $\phi$ (eV) \| 2.4 \| 2.3 \| 2.2 \| 3.7 \| 4.8 \| 4.3 \| 4.7 \| 6.3 \| 4.75 \|

Answer: 4

💡 Solution & Explanation

Energy of incident photon $E = \frac{1240 \text{ eV}\cdot\text{nm}}{300 \text{ nm}} \approx 4.133$ eV. For photoelectric emission to occur, the incident energy must be greater than the work function ($E > \phi$). The metals satisfying this condition are Li (2.4 eV), Na (2.3 eV), K (2.2 eV), and Mg (3.7 eV). There are 4 such metals. Therefore, correct answer is 4.

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