Can someone me with my physics questions? i need correct answers only! free fall is a situation in which the only force acting upon an object is gravity. why do all objects in free fall have the same acceleration? a) their masses are always the same b) acceleration due to gravity is always the same c) the distance between two objects is always the same d) the gravitational force between two objects are always the same

According to the experiments done and currently verified, in vacuum (this means there is not air or any fluid), all objects in free fall experience the same acceleration, which is the acceleration of gravity.  

Now, in this case we are on Earth, so the gravity value is  

Note the objects experience the acceleration of gravity regardless of their mass.

Nevertheless, on Earth we have air, hence air resistance, so the afirmation "Free fall is a situation in which the only force acting upon an object is gravity" is not completely  true on Earth, unless the following condition is fulfiled:

If the air resistance is too small that we can approximate it to zero in the calculations, then in free fall the objects will accelerate downwards at and hit the ground at approximately the same time.  

igneous rocks also form where plates converge. the subducting plate melts as it sinks into the crust of the earth, and the melt rises into the overriding plate forming volcanoes. metamorphic rocks are formed mainly in the lithosphere, wherever there is high pressure and high temperature. -woods