Mariam's mother had an ultrasound to see the baby growing inside of her. which statement explains how ultrasound works?

Identify one disadvantage to each of the following models of electron configuration: dot structures arrow and line diagrams written electron configurations type in your answer below.

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.

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