Acertain element (x) has isotopes with mass numbers of 10 and 11. the x-10 isotope has an atomic mass of 10.013, and it represents 19.9% of all atoms of this element. the x-11 isotope has an atomic mass of 11.009, and it represents 80.1% of all atoms of this element. therefore, the average atomic mass, or atomic weight, of this element is amu.

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.