The PH of a solution can be measured using the H+ ions concentration present in the solution. PH= -log(H+) H+ is the hydrogen ion concentration. or by knowing the OH- ion concentration. PH= 14- (-log(OH-)-log(OH-) is the pOH of the solution.
If you see a brown patch under the stem it's going to be a little gross inside. If you see a nice yellow-green patch you have a perfectly ripe avocado. Just make sure nobody at the grocery store notices you flicking the stems off a ton of avocados.
The average California Hass avocado weighs between 165-170 grams (about 6 ounces) and has a pebbled dark green or black skin. Other varieties can have different textures (for example, smoother and less pebbly), different colors (for example, lighter or brighter greens), and varying degrees of glossiness.