With regard to sound waves, which one among the following is correct ?

Sound waves are longitudinal mechanical waves, meaning they require a material medium (solid, liquid, or gas) to propagate. They cannot travel through a vacuum, which makes Option D incorrect. Unlike light waves, which are transverse, sound waves in fluids travel as a series of compressions and rarefactions, making Option A incorrect.

• Option B is correct: Sound waves follow the same laws of reflection as light. The angle of incidence equals the angle of reflection, and the incident wave, reflected wave, and the normal at the point of incidence all lie in the same plane. This principle is utilized in devices like megaphones and soundboards.
• Option C is incorrect: In general, sound travels fastest in solids and slowest in gases. While the speed of sound is inversely proportional to the square root of density, it is directly proportional to the square root of the medium's elasticity. Because solids are significantly more elastic than gases, sound travels much faster in denser media like steel than in air.