<p>Suppose a pure Si crystal has&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>6</mn><mo>&#215;</mo><msup><mn>10</mn><mn>28</mn></msup></math>&nbsp;atoms/m&sup3;. It is doped by 1 ppm concentration of pentavalent As. Calculate the number of electrons and holes, Given that&nbsp;ni=<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>0</mn><mo>.</mo><mn>5</mn><mo>&#215;</mo><msup><mn>10</mn><mrow><mn>16</mn><mo>&#160;</mo></mrow></msup><msup><mi>m</mi><mrow><mo>-</mo><mn>3</mn></mrow></msup></math>.</p>