Help with 16,17

16. The mass of Mercury is 3.2 x 1023 kg and its radius is 2.43 x 106 m. What is the acceleration due to gravity on this planet? A) 9.81 m/s2 B) 3.61 m/s2 C) 1.60 m/s2 D) 5.77 m/s2 17. A satellite is in a stationary orbit above the Earth, which has a mass of 5.98 x 1024 kg. If the satellite is geosynchronous (period = 24 hours), how far from the surface of the Earth would it be located? A) 4.23 x 104 km B) 3.59 x 104 km C) 956 km D) 7.80 x 104 km