Can someone please help me with this question

Wind and moving water provide energy. chemical mechanical thermal none of the above

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

Calculate the ph of a .10m nh4cl solution. the kb value for nh3 is 1.8×10^-5