<span>Class and Family is the answer
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The property of semiconductors that makes them most useful for constructing electronic devices is that their conductivity<span> may easily be modified by introducing </span>impurities<span> into their </span>crystal lattice<span>. The process of adding </span>controlled impurities<span> to a semiconductor is known as </span>doping<span>.</span>
Heating of the Earth due to the Sun's rays causes convection currents of air upwards. The warm air moves upwards, while cool air from nearby regions fills in the lower areas.
<span>Heating of the Earth can cause warm water currents that flow from hot areas like near the equator and tropical areas, while cold water currents flow from the arctic and antarctic regions and the temperate regions. </span>