Which of the following is not true of alloys?
a. alloys are made of two or more metals combined physically.
b. the mixture of metals in an alloy is based upon the desired use.
c. alloys can be substitutional or interstitial.
d. an example of an alloy is copper.

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Ahypothrticalax type of ceramic material is known to have a density of 2.10 g/cm3 and a unit cell of cubic symmetry with a cell edge length of 0.57 nm. the atomic weights of the a and x elements are 28.5and 30.0 g/mol, respectively. on the basis of this information, which of the following crystal structures is (are) possible for this material: sodium chloride, cesium chloride, or zinc blende

Gymnast always perform on padded mats. how does the mats protect the gymnast