Some materials are phosphorescent, meaning that they can absorb light energy from the Sun, and then re-emit this energy later. Many objects people use today are phosphorescent, including glow-in-the-dark plastics. Some plastic objects have phosphorescent materials in them, which causes them to glow after they are exposed to light. In 1896, one year after x-rays were discovered, scientist Henri Becquerel hypothesized that uranium might work in this way as well. So he exposed a sample of uranium to sunlight, and then was pleased to discover that the uranium continued to emit energy even after it was taken out of the light. However, after several straight days of cloudy skies over his laboratory, Becquerel was shocked to discover that the energy kept coming from the uranium, even without sunlight. What had Becquerel accidentally discovered?

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

This chart lists four kinds of polymers and their sources. what can be known about all four polymers, despite their differences? they come from living things. they share ionic carbon bonds. they are at least 100 monomers long. they are made of repeating subunits.

The excretory system, need answers for all: )