Can u tell me the steps to measure a straight line.. need answer immediately..

First get a pencil, this is better incase you need to erase.
Then get a straight edge object. (ruler, book, or another pencil :)
Then lay down the object (ruler, book, or pencil) on the item you will draw the straight line on.
Holding your pencil steady, trace the edge of the item you will use to help you draw the straight line.

Hope this helps!

Neither model is able to show the reactivity of potassium.