Is copper wire a mixture or a pure substance?

What is the ima of the 1 st class lever in the graphic given? 2 3 0.5

The ammonia molecule in the diagram has the observed bond orientation because

Magnesium is the limiting reactant in this experiment. calculate the theoretical yield of mgo for each trial. trial 1: trial 2: data mass of empty crucible with lid trial 1: 26.688 trial 2: 26.681 mass of mg metal, crucible, and lid trial 1: 26.994 trial: 2 26.985 mass of mgo, crucible, and lid trial 1: 27.188 trial 2: 27.180