I might quit because people are just using me for my points. could someone answer this for me?

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

The bond energy for the van der waals bond between two helium atoms is 7.9×10−4ev. assuming that the average kinetic energy of a helium atom is (3/2)kbt, at what temperature is the average kinetic energy equal to the bond energy between two helium atoms

Mary is conducting an experiment on how pollution affects plant growth. how can she ensure that her data are reliable?