Discover Questions

Astronomers, who takes pictures of galaxies?!! How long does it take for a camera man to travel to this point to take a picture?!? What percentage of Earth is uninhabitable? Let S={-1,2,5,8,…, 161,164} find the least positive integer m such that for every A⊆S,|A|=m there are at least two elements a,b⋹A, a+b=160? Why does Na2CO3have a higher conductivity than all of the other electrolytes? What is the weight of 20 sheets of copier paper?