All main sequence stars are fusing hydrogen into helium in their cores all main sequence stars are using the same set of reactions in their cores both of the first two statements are true neither of the first two statements are true

For these two statements they would both be true. Main sequence stars fuse hydrogen into helium, and all main sequence stars use these reactions in their cores to power their nuclear fusion.

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.