Mixture typically melt at different temperature than the pure substance they are composed of. Brass is a of copper and zinc, and it melts at temperature between 820 degrees Celsius (°C) and 1030 degrees Celsius (°C). Why might different samples of brass melt at different temperatures?

Disinfection of impression materials is usually accomplished by a. sterilization with high heat. b. spray or immersion in a chemical disinfectant. c. sterilization with steam under pressure. d. allowing the impression to sit 24 hours in water until all the organisms die.

Some birds look for food near cattle and other livestock. the movement of the cattle churns up the ground, making insects available to the birds. the cattle appear to be unaffected by the presence of the birds. what kind of relationship exists between the birds and the cattle? o a. parasitism o b. commensalism o c. predation o d. mutualism

All but one describes an effect of aging on the digestive system. a) decreased acid secretion b) decreased elasticity of stomach c) capacity to resist damage decreases d) food remains in stomach for less time