28. Which commonly used structural metal has the lowest density? a. aluminum b.

Question

28. Which commonly used structural metal has the lowest density? a. aluminum b. zinc e. magnesium d. titanium 29. Calcium oxide from oyster shells is used to precipitate magnesium from sea water. The oxide reacts with water to form a. hydrogen b. a sulfate c. a hydroxide d. oxide ions which precipitate the magnesium in the aqueous medium 30. Roasting of metal ores In air a. converts sulfides to oxides b. converts sulfides to pure metals c. converts oxides to silicates d. reduces metal oxides to sulfides 31. Most metals are found in the Earth as a. positive ions b. negative ions c. neutral atoms d. molecules 32. What can be melted with silica (silicon dioxide)to form common window glass? a. carbon b. carbonates of sodium and calcium c. sodium sulfate and sodium sulfite d. sand containing small amounts of magnesium 33. Clay is a hydrated mixture of the oxide, of a. iron and silicon b silicon and calcium c. iron and calcium d. aluminum and silicon 34. Which of the following is not an ingredient in Portland cement? a. anhydrous calcium oxide b. silicon dioxide c. hydrated calcium sulfate d. aluminum oxide 35. Glass is annealed so that a. silicon is baked out of the mixture b. calcium carbonic is decomposed to form calcium oxide c. strain is minimized as the liquid cools d. none of these 36. Amorphous materials a. are solids like tar and glass that have no internal order b. are solids with regular order c. have a definite crystal structure d. are crystalline solids

Explanation / Answer

Sol: 28) Ans: C (Magnesium)
   29) Ans: C (a hydroxide)
30) Ans: A (converts sulphides to oxide)
   31) Ans: A (positive ion in their compounds like oxides.....)
   32) Ans: B (carbonates of sodium and calcium)
33) Ans: A (auminium and silicon)
   34) Ans: C (hydrated calcium sulphate)
   35) Ans: C (strain is minimized as the liquid cools)
   36) Ans: A(are solids like tar and glass that have no internal order)

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