This study investigates the intrinsic and extrinsic performance limits of graphene devices on SiO₂. The linear dispersion relation in graphene leads to a surprising prediction that the resistivity due to isotropic scatterers is independent of carrier density. The research shows that acoustic phonon scattering is indeed independent of carrier density and sets an intrinsic resistivity limit of 30 Ω at room temperature. At a carrier density of 10¹² cm⁻², the mean free path for electron-acoustic phonon scattering is over 2 microns, and the intrinsic mobility limit is 2×10⁵ cm²/Vs, exceeding that of inorganic semiconductors and carbon nanotubes. Extrinsic scattering from SiO₂ surface phonons adds a temperature-dependent resistivity above ~200 K, limiting the room temperature mobility to ~4×10⁴ cm²/Vs. The study measures the four-probe resistivity of graphene devices on SiO₂/Si across a wide temperature range and gate voltage. The resistivity is found to be linear in temperature at low temperatures, with a slope independent of carrier density. Acoustic phonon scattering is modeled, and the results agree with theoretical and experimental expectations. The temperature-dependent resistivity is also explained by an activated contribution, which is attributed to remote interfacial phonon (RIP) scattering from the SiO₂ substrate. The data show that the resistivity is proportional to Vg⁻¹·⁰⁴, consistent with RIP scattering. The intrinsic and extrinsic limits to the resistivity and mobility in graphene are determined by analyzing the contributions of acoustic phonons and RIP scattering. The study concludes that the room-temperature intrinsic resistivity of graphene is 30 Ω, and the mobility is limited by extrinsic RIP scattering. The results suggest that with proper substrate choice or suspension, the intrinsic mobility limit of 2×10⁵ cm²/Vs could be achieved, enabling ballistic transport over micron lengths and new electronic devices based on quantum transport at room temperature.This study investigates the intrinsic and extrinsic performance limits of graphene devices on SiO₂. The linear dispersion relation in graphene leads to a surprising prediction that the resistivity due to isotropic scatterers is independent of carrier density. The research shows that acoustic phonon scattering is indeed independent of carrier density and sets an intrinsic resistivity limit of 30 Ω at room temperature. At a carrier density of 10¹² cm⁻², the mean free path for electron-acoustic phonon scattering is over 2 microns, and the intrinsic mobility limit is 2×10⁵ cm²/Vs, exceeding that of inorganic semiconductors and carbon nanotubes. Extrinsic scattering from SiO₂ surface phonons adds a temperature-dependent resistivity above ~200 K, limiting the room temperature mobility to ~4×10⁴ cm²/Vs. The study measures the four-probe resistivity of graphene devices on SiO₂/Si across a wide temperature range and gate voltage. The resistivity is found to be linear in temperature at low temperatures, with a slope independent of carrier density. Acoustic phonon scattering is modeled, and the results agree with theoretical and experimental expectations. The temperature-dependent resistivity is also explained by an activated contribution, which is attributed to remote interfacial phonon (RIP) scattering from the SiO₂ substrate. The data show that the resistivity is proportional to Vg⁻¹·⁰⁴, consistent with RIP scattering. The intrinsic and extrinsic limits to the resistivity and mobility in graphene are determined by analyzing the contributions of acoustic phonons and RIP scattering. The study concludes that the room-temperature intrinsic resistivity of graphene is 30 Ω, and the mobility is limited by extrinsic RIP scattering. The results suggest that with proper substrate choice or suspension, the intrinsic mobility limit of 2×10⁵ cm²/Vs could be achieved, enabling ballistic transport over micron lengths and new electronic devices based on quantum transport at room temperature.