The speed of sound is faster in:

Sound waves are mechanical longitudinal waves that require a material medium to propagate. The speed of sound depends on the density and elasticity of the medium ($v=\sqrt{\frac{Y}{\rho }}$ or $\sqrt{\frac{B}{\rho }}$). Because solids possess much higher elastic moduli than liquids or gases, sound travels fastest in solids. Sound cannot travel in a vacuum at all.