How many significant figures are in 100.3

In which layer of earth do most earthauakes occur a_ inner core b_outer core c_mantle d_crust

What is the mass defect of a mole of nuclei with 1.8 x 10^15 j/mol binding energy?

For the reaction shown, find the limiting reactant for each of the following initial amounts of reactants. 4al(s)+3o2(g)→2al2o3(s) a) 1 molal, 1 mol o2 b) 4 molal, 2.6 mol o2 c) 16 molal, 13 mol o2 d) 7.4 molal, 6.5 mol o2