U-238, the common isotope of uranium, has 92 protons, 146 neutrons, and 92 electrons. u-235 is another isotope of uranium. how do the number of subatomic particles of u-238 and u-235 differ? a. u-238 has three more electrons than u-235. b. u-238 has three more neutrons than u-235. c. u-238 has one more proton and two more neutrons than u-235. d. u-238 has one more electron and two more protons than u-235. how are mixtures different from compounds? a. mixtures combine to produce salts; compounds do not. b. mixtures can be separated by physical means; compounds cannot. c. mixtures combine several different elements; compounds only combine one element. d. mixtures involve particles that can be seen, like sand; compounds involve particles that cannot be seen, like air.