the ppm scale is defined as the ~~ration ~~ratio between a variation of resonance frequency and a reference resonance frequency. The ppm range of 13C is bigger than ppm range of 1H because little perturbation of electronic environment of 13C is bigger compared to the major ~~the ~~contribution of Larmor frequency. The gyromagnetic ratio is 4 times lower for 13C. So if the perturbation is identical for 1H and 13C, the range have to be 4 times bigger. We see that is 10 times bigger, so an other contribution exist, likely a more susceptibility of electronic density to be disturbed...