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  • How to solve this problem- - Atomic Structure - JEE Main

The energy required to break one mole of Cl-Cl bonds in Cl_{2}\: is\: 242\: kJ mol^{-1}. The longest wave-length of light capable of breaking a single Cl-Cl bond  is

\left ( c= 3\times 10^{8} m\: s^{-1}\: and \: N_{A}= 6.02\times 10^{23}mol^{-1}\right )

  • Option 1)

    494 nm

  • Option 2)

    594 nm

  • Option 3)

    640 nm

  • Option 4)

    700 nm

 

Answers (2)

As we learnt in 

The energy (E) of a quantum of radiation -

E=hv

Where h is plank’s constant and \nu is frequency

-

 

Energy\:of\:one\:photon = \frac{242 \times 10^3}{ 6.02 \times 10^23} = E

E = \frac{hc}{\lambda}

\lambda = \frac{hc}{E} = \frac{6.63 \times 10^{-34} \times 3 \times 10^8 \times 6.02 \times 10^23}{242 \times 10^3}

\lambda = 4.94 \times 10^{-7} = 494 nm

 


Option 1)

494 nm

Correct

Option 2)

594 nm

Incorrect

Option 3)

640 nm

Incorrect

Option 4)

700 nm

Incorrect

Posted by

Vakul

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