HURRY PLS WHAT DOES THIS MEAN

Which function is performed by earths atmosphere? a. ultraviolet rays are prevented from reaching the ozone layer. b. earths temperature is raised and moderated by trapping in heat c. charged particles from the sun are prevented from reaching earth. d. magnetic charges from space are prevented from reaching earths surface.

In saturated organic compounds, all the bonds between carbon atoms are called?

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.