The predictions on the α-decay chains of the isotopes of the superheavy nuclei with Z = 120 in the range 272 A 319 have been done within the Coulomb and proximity potential model for deformed nuclei. A comparison of our calculated α half-lives with the values computed using the Viola-Seaborg [J. Inorg. Nucl. Chem. 28, 741 (1966)] systematic, the universal curve of Poenaru et al. [Phys. Rev. C 74, 014312 (2006)], and the analytical formulas of Royer [J. Phys. G: Nucl. Part. Phys. 26, 1149 (2000)] show good agreement with each other. An extensive study on the spontaneous fission half-lives of all the isotopes under study has been performed to identify the mode of decay of these isotopes. The study reveals that the α-decay half-lives and the mode of decay of the isotopes of 298,299 120, which are evaluated by using our formalisms, agree well with the experimental observations of Oganessian et al. [Phys. Rev. C 79, 024603 (2009)]. Our study on the isotopes of Z = 120 predicts that the α decay restricts within the range 277 A 308 as those isotopes with A 276 and those nuclei with A 309 do not survive fission. We have also forecasted the mode of decay of 288−302 120 superheavy nuclei as six consistent α chains from the nuclei of 288,289,291−295 120, seven consistent α chains from the nuclei of 290 120, five consistent α chains from the nuclei of 296,297 120, and three consistent α chains from the nuclei of 300−302 120, which could be of great interest to the experimentalists. The one-proton and two-proton separation energy calculations on 272−319 120 superheavy nuclei have revealed that the isotopes spanning the range 273 A 291 may be considered to be the probable proton emitters.