What is the only force acting on an object orbiting earth

Iknow the answer is a but i don't know why

Which type of bond is present in hydrogen sulfide (h2s)? the table of electronegativities is given. a. hydrogen b. ionic c. nonpolar covalent d. polar covalent

Lem 2 the data below are for the system ethyl propyl ether (1)-chloroform (2) at 0.5 bar. use the data to answer the following questions (all questions refer to p d 0: 5 bar). a) what are the boiling points of the pure components at 0.5 bar? b) a mixture with the overall composition z1 d 0: 1 is brought to 47.6ä±c, 0.5 bar. what is the phase? c) 100 mole of a mixture with z1 d 0: 1 (state a) is mixed with 22 mole of pure ethyl propyl ether vapor (state b). the mixing takes place at 47.6 ä±c, 0.5. bar. what is the phase of the resulting mixture (state c)? if the state is a v/l mixture report the number of moles and mole fractions in each phase. d) plot the txy graph and show states a, b and c. the graph must be done by computer and should be properly annotated. ethyl propyl ether (1) - chloroform (2) at 0.5 bar t ( ä±c) x1 y1 t ( ä±c) x1 y1 42.9 0.000 0.000 49.0 0.470 0.455 43.0 0.020 0.010 49.1 0.520 0.520 43.9 0.065 0.029 48.9 0.567 0.592 45.4 0.156 0.089 48.3 0.652 0.720 46.4 0.215 0.142 47.6 0.745 0.815 47.6 0.296 0.223 46.7 0.822 0.872 48.3 0.362 0.302 45.7 0.907 0.937 48.7 0.410 0.375 44.6 1.000