Assertion : The de - Broglie wavelength of a molecule varies inversely as the square root of temperature.
Reason : The root mean square velocity of the molecule depends on the temperature.

Options

A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true and R is NOT the correct explanation of A
C. A is true but R is false
D. A is false and R is true

Answer

A

Explanation

`v_(RMS)= sqrt((3RT)/(M))`
So, `v_(RMS) prop sqrt""T`
Again de-Broglie wavelength, `lamda= h//mv`
So, `lamda prop 1//sqrt""T`
Hence, assertion and reason both are true and reason explains the assertion.