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 Home > JCEDLib > QBank > Collection > CQs and ChPs > CQs > CQ Library >
Library of Conceptual Questions (CQs): Introductory Material

A blue crystalline material is heated strongly in a test tube. A clear liquid condenses around the mouth of the tube and the crystals gradually lose their blue color and become white powder. Every gram of blue crystal produces 0.36 g of clear liquid and 0.64 g of colorless powder. The same behavior is observed for samples of the crystals taken from many different sources. These observations are consistent with the hypothesis that the blue crystals are

(a) a solution
(b) a compound
(c) a wet salt
(d) an element
(e) a heterogeous mixture

Source: Fred Senese, Frostburg State Univeristy.

Antoine Lavoisier, the "father of chemistry", listed lime as a chemical element in his table of 33 known elements. Which of the following observations best shows that lime cannot be an element?

(a) Lime reacts with water, generating a large amount of heat.
(b) Lime and carbon dioxide are produced when limestone is roasted.
(c) When a certain soft metal is burned in oxygen, lime is produced (with no other products).
(d) Lime melts at a temperature of 2572°C.

Source: Fred Senese, Frostburg State Univeristy.

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