1.) A sample of concrete contains cement, gravel, crushed rocks, sand, and water. Each of these contains different metals and minerals and hence has different colors and different properties. Which term or terms could be used to describe this sample of concrete? 2.) A silver necklace is made from a pure sample of silver that is free of impurities. Which term or terms could be used to describe this sample of silver? Choices: mixture heterogeneous mixture homogenous mixture solution pure chemical substance compound element