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AIEEE 2010 Solved Paper

Section: Chemistry

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Question : 1 of 89

Marks: +1, -0

The energy required to break one mole of

\mathrm{Cl}-\mathrm{Cl}

\mathrm{Cl}_2

242\ \mathrm{kJ}\ \mathrm{mol}^{-1}

. The longest wavelength of light capable of breaking a single

\mathrm{Cl}-\mathrm{Cl}

(c = 3 \times 10^8\ \mathrm{ms}^{-1}

N_{\mathrm{A}} = 6.02 \times 10^{23}\ \mathrm{mol}^{-1})

594 nm
640 nm
700 nm
494 nm

Solution:

Energy required to break one

\mathrm{Cl}_2

molecule

= \frac{242 \times 10^3}{6.02 \times 10^{23}}\ \mathrm{J}

\text{As}\ E = \frac{h c}{\lambda}

So

\lambda = \frac{h c}{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}\ \mathrm{m}

= 494\ \mathrm{nm}

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