PLEASE ANSWE

Label friction, conduction, or induction

1. rubbing a balloon on hair
2. touching a metal sphere with a negatively charged rod
3. moving a negatively charged rod near a metal sphere that is grounded
4. touching a metal sphere with a positive aluminum plate

Icant see the pictures 

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

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.