According to ekman, the most long-distance communicator of emotion is:

Smile

Explanation: According to the theory of Ekman, Smile is defined in the manner of acting as factor for communication for long distance . It indicates about the differentiating the zygomatic muscles and the orbicularis oculi muscle from each other.

This leads to the phenomena of occurring immediate happiness and enjoyment in the form of smile that is denoted by the name of Duchenne smile.This smile is considered to be smiling along with the eyes.

c. taught scientists many new things about the earth, but not other planets.

explanation:

question - in 1827, john walker, a druggist in a small english town, tipped a splint with sulphur, chlorate of potash, and sulphid of antimony, and rubbed it on sandpaper, and it burst into flame. the druggist had discovered the first friction-chemical match, the kind we use to-day. it is called friction-chemical because it is made by mixing certain chemicals together and rubbing them. although walker's match did not require the bottle of acid, nevertheless it was not a good one. it could be lighted only by hard rubbing, and it sputtered and threw fire in all directions. in a few years, however, phosphorus was substituted on the tip for antimony, and the change worked wonders. the match could now be lighted with very little rubbing, and it was no longer necessary to have sandpaper upon which to rub it. it would ignite when rubbed on any dry surface, and there was no longer any sputtering. this was the phosphorus match, the match with which we are so familiar. according the paragraph what was the benefit of the new phosphorus match? it burst into flame when rubbed on sandpaper. it was made by mixing chemicals. it could be ignited on any dry surface. it threw fire in all directions.

answer - matches required natural chemicals