An element has three naturally occurring isotopes. the relative abundances of the isotopes are 0.27%, 9.25%, and 90.48%. the most abundant isotope has an atomic mass of 19.99 amu. the least abundant isotope has an atomic mass of 20.99 amu, and the remaining isotope has an atomic mass of 21.99 amu. based on these data, what is the average atomic mass of this element? (round your answer to the nearest hundredth and do not enter units in your answer.)

Identify which properties could correspond to solids, plasmas, or both. maintain a unique shape. collide infrequently with other particles. have very high velocities. conduct electricity. protons. have a low temperature. has long-range order.

Which statement describes how phase changes can be diagrammed as a substance is heated? the phase is on the y-axis and the temperature is on the x-axis. the temperature is on the y-axis and the phase is on the x-axis. the time is on the y-axis and the temperature is on the x-axis. the temperature is on the y-axis and the time is on the x-axis.

Astudent made a graph plotting the progress of a reaction over time. the student forgot to label the y-axis of the graph. a graph is shown with two graph lines. one graph line starts at a higher position on the y axis and slopes downwards towards the right. the other graph line starts at a lower position on the y axis and slopes upwards towards the right. the two graph lines stop short of intersecting each other and continue as separate lines which gradually become straight and parallel to the x axis. a vertical line is shown at a point where the two graph lines finally became parallel to the x axis. this vertical line is labeled equilibrium. the title on the x axis is time and an arrow pointing towards the right is shown above time. the title on the y axis is left blank. what best explains the label that the student should use on the y-axis? amount, because as the amount of product decreases, the amount of reactant increases over time. reaction rate, because forward and backward reaction become equal at equilibrium. amount, because the amounts of reactants and products become constant after equilibrium is reached. reaction rate, as the rate of forward reaction increases and rate of backward reaction decreases over time.