The pKa of propanoic acid (propionic acid), CH3CH2COOH, is 4.87. Consider an equilibrium mixture of propanoic acid and its conjugate base with a pH of 4.87. Draw the structure of the form (acid or conjugate base) that predominates after a decrease in [H3O ]. Include all hydrogen atoms and any appropriate formal charges.

They are all full and don't need any more electrons in there outer shell.

Combustion is the act or process of burning. therefore, i believe the answer is  a: burning wood. 

That is a lot of moles that you have

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.