Chemical evidence for chain folding in polyethylene crystals is obtained by etching polymer crystals with fuming nitric acid, which cleaves the chain at the fold surface. the resulting chain fragments are separated chromatographically and their molecular weights determined by osmometry. the folded chain is pictured as crossing through the crystal, emerging and folding back, then reentering and recrossing the crystal, and so on. according to this picture, the shortest chain showing up in the chromatograms should equal the crystal thickness in length. the second shortest chain exceeds twice this value by some amount, which measures the length of the loop made by the chain outside the crystal. molecular weights for the two shortest chains observed in an experiment of this sort were 1260 and 2530. since the cleaved chains end in nitro and carboxyl groups, 60 should be subtracted from each of these molecular weights to give polyethylene chain weight. calculate the degree of polymerization of each molecule and the chain length (use the length of the unit cell along the chain axis, 2.53 å, as the distance per repeat unit). compare the latter with the crystal thickness determined by x-ray diffraction, 105 å. what does the ratio of chain lengths for the first and second peaks suggest about the tightness of folding

Write a paragraph that provides examples of each stage of volcanic activity, a description of the volcano, and facts about each stage.

Quickly! brainliest if two people answer! 1. the blood has red blood cells, white blood cells and platelets. red blood cells carry oxygen to other cells in the body. cells need oxygen to live. white blood cells destroy certain germs. they protect our bodies from disease. which question is answered in this paragraph? (a) what is the role of blood vessels? (b) what type of cells are attached to bones? (c) what type of blood cell to clot your blood? (d) what are the different types of blood cells? 2. which sentence from the section "stem cells" best explains the role of stem cells? (a) when one kind of cell stops working, stem cells can . (b) they can turn into that cell and take its place. (c) scientists are studying new ways to use stem cells. (d) these cells can people heal faster. 3. read the selection from the section "nerve cells." nerve cells send messages to the rest of our bodies. these messages move between the brain, spinal cord and various organs. nerve cells are also called neurons. fill in the blank. a "neuron" is a (a) cell that moves information from the brain to other parts of the body (b) stem cell that has both an axon and a dendrite (c) cell that controls the fingers of a body (d) cell that makes up the spinal cord 4. some muscles in our body move without us telling them to. these are called involuntary muscles. some examples are the cardiac muscle cells inside the heart. these cells the heart relax and fill with blood. what is the best definition of "involuntary" based on the context clues? (a) something that happens on its own (b) trying hard to do something (c) something moving back and forth (d) easily moved

Sugar is dissolved in water. which is the solute? sugar neither both water