Answer:
An extreme version of scoria occurs when volatile-rich lava is very quickly quenched and becomes a meringue-like froth of glass called pumice. Some pumice is so full of vesicles that the density of the rock drops low enough that it will float
Explanation:
The typical light microscope at its maximum magnification power has a resolution of 200 nm. The light microscope is able to view and distinguish between two lines or points that are no less than 200 nm apart. Since our membrane of interest is 8 nm apart, it won't be visible under the light microscope. Several such membranes are needed to lined side by side to make the viewing possible. The number of membranes should be, 
= 25.
At the start of prophase I, the chromosomes have already duplicated. During prophase I, they coil and become shorter and thicker and visible under the light microscope.
For the answer to the question above, I believe the answer is
intravenous pyelogram (IVP)It is <span>an x-ray examination that uses injection of contrast material to evaluate your kidneys, ureters, and bladder and to help diagnose the blood in the urine or pain in your side or lower back.</span>
