There are total 8 planets in our Solar System . Every Day Science Questions on our Solar System Smallest and largest planet . Each planet has two things mass and volume . So from all the planets Mercury has less mass and volume among the other planets. Diameter of the Mercury is 4,879 KMs, Mercury has mass of 330x 10 23 KGs and Volume of 14.6 trillion Cubic Miles. Multiple Choice Questions MCQs and Answers on Solar System General Science and Ability.