Assertion : The root mean square and most probable speeds of the molecules in a gas are the same. Reason : The Maxwell distribution for the speed of molecules in a gas is symmetrical.

• A

  If both assertion and reason are true and reason is the correct explanation of the assertion
• B

  If both assertion and reason are true but reason is not the correct explanation of the assertion
• C

  If assertion is true, but reason is false
• Correct answer
  D

  Both assertion and reason are false statements.

Solution

$$ \begin{gathered} \text { } v_{\text {r.m.s }}=\sqrt{\frac{3 k T}{m}} \text { or, } \sqrt{\frac{3 R T}{M}} \\ v_{\text {probable }}=\sqrt{\frac{2 k T}{m}} \text { or, } \sqrt{\frac{2 R T}{M}} \end{gathered} $$ $\therefore$ Assertion is wrong.

Hence, the correct answer is option: 'D'.