Because if you don't, how will people know what the explanatory variable is?
The horizontal axis is always your x-axis. So just put an X next to your x-axis and you've labelled it.
X axis is horizontal, and The Y axis is vertical.
the independent variable
It depends on your question
"atomic weight" is always on the x-axis of the mass spectrum graph.
posotive/ negative numbers
Just label one axis x and the other axis y. Voila!! x y graph!
the title, Y Axis X axis label and/or legend. (this either replaces the "X axis" making it just "axis" , or its just a wrong answer.
axis labels are x and y while bar graph labels explain what the graph is representing.
On a vertical axis you should label it the "y-axis". Then make sure to put the numbers needed on the line! :)
x-axis
The independent variable is plotted on the horizontal axis, or x axis. The dependent variable, or response variable is plotted on the vertical axis, or y axis.