QJEEM25Phefd4: JEE Main 2025 Physics - Class 11 JEEM25Phefd4 Solution: Given below are two statements: one is labelled as and the…

Question

Verified Solution • 2025–26 Session moderate

Given below are two statements: one is labelled as $\mathbf{A s s e r t i o n} \mathbf{A}$ and the other is labelled as Reason $\mathbf{R}$

Assertion A: A sound wave has higher speed in solids than gases.

Reason R: Gases have higher value of Bulk modulus than solids.

In the light of the above statements, choose the correct answer from the options given below

A Both $\mathbf{A}$ and $\mathbf{R}$ are true and $\mathbf{R}$ is the correct explanation of $\mathbf{A}$
B $\mathbf{A}$ is false but $\mathbf{R}$ is true
C $\mathbf{A}$ is true but $\mathbf{R}$ is false
D Both $\mathbf{A}$ and $\mathbf{R}$ are true but $\mathbf{R}$ is NOT the correct explanation of $\mathbf{A}$

Accepted Answer

We know, speed of sound in a medium $v = \sqrt {{B \over \rho }}$ where B = bulk modulus, $\rho$ = density of the medium

Since, solids and liquids are much more difficult to compress than gases so they have much higher values of bulk modulus.

i.e., ${B_{solid}} > {B_{liquid}} > {B_{gas}}$

Generally solids and liquids have higher mass densities ( $\rho$ ) than gases. But corresponding increase in bulk modulus is much higher.

So, ${v_{solid}} > {v_{liquid}} > {v_{gas}}$

Hence, option 3 is correct.

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