Aprediction of the theory of plate tectonics is that new volcanoes can form at the boundary of two plates as magma seeps between them. to test this hypothesis, a scientist makes a map of existing volcanoes along a tectonic plate and measures the number of new volcanoes that appear over a decade. what would be the expected result of the experiment? how would you interpret the results if the scientist observes no new volcanic activity?

For the map part drawing, the scientists will find that a very large number of volcanoes are situated close to the points of the meeting of the tectonic plates. The volcanoes not present at the edge of the plates now were possibly at the moment of their development and were moved away due to the movement of the plate. However, the scientist would not be able to find the new volcanoes as the development of a volcano is not something that occurs in a night.  

In case if the scientist does not witness new volcanic activity, it does not invalidate the theory as the period of observation is very brief. Ten years is not a substantial time period if seen geologically. The study would have to be performed for at least 1000 years to demonstrate some kind of result.