12th Class Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Assertion And Reason (MCQs) - Dual Nature of Radiation and Matter

  • question_answer
    Assertion (A): de-Broglie wavelength of a gas molecule is inversely proportional to the square root of temperature.
    Reason (R): The root mean square velocity of gas molecules depends on temperature.

    A) Both A and R are true and R is the correct explanation of A

    B) Both A and R are true but R is NOT the correct explanation of A

    C) A is true but R is false

    D) A is false and R is true

    Correct Answer: A

    Solution :

    Option [a] is correct
    Explanation: \[{{v}_{\operatorname{RMS}}}=\sqrt{\frac{3RT}{M}}\]
    So, \[{{v}_{\operatorname{RMS}}}\propto \surd \operatorname{T}\]
    Again de-Broglie wavelength, \[\lambda =h/mv\]
    So, \[\lambda \propto 1/\surd T\]
    Hence, assertion and reason both are true and reason explains the assertion.           


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