4Fe + 3O2 2X
Which compound is represented by X?

The answer is b metal denting

Following are the  advantages of the parametric equations: 1) they can be used to graph curves that are not functions, like the unit circle.2) the parameter can be used to represent the quantity that is  useful to  provide us with better information about the graph.3)  it is useful to convert between rectangular equations and parametric equations.with specific reference to chemistry,  parametric equations are employ for solving hydrogen and hydrogen-like ions, quantum mechanically. herein, cartesian coordinates are converted in spherical polar coordinates. the solution obtained, when plotted on spherical polar graph paper, provides visualization of atomic orbital such as s,p,d and f. 

Silicon  6.0x10^23 is avogadro's number so the answer has to be 1 mole of whatever it is. since the molarity of silicon is equal to 28g/mol, this has to be the answer because 28g of si is 1 mole of si.