When an apple falls from a tree, when does gravity act on the apple?

Which of the following true? a_volcanoes and earthquakes often near the plate boundaries. b_volcanoes occur whereve there are tall mountains. c_earthquakes cause volcanoes in the same location to erupt violently d_volcanoes and earthquakes occur only where plates are colliding with each other

How might this scientific phenomena be explained? a paper clip floats on water.

The term gas is limited to those substances that exist in the gaseous state at