Boron carbide, B, C is made by the high temperature reaction of boron oxide with
ID: 492752 • Letter: B
Question
Boron carbide, B, C is made by the high temperature reaction of boron oxide with graphite, yielding carbon monoxide as a by-product. _B_2 O_3 + C rightarrow B_4 C + __CO What is the total of the smallest coefficients for the reactants and products in the balanced equation? (A) 9 (B) 10 (C) 15 (D) 16 A compound with 69.41% C, 4.16% H and 26.42 % O has a molar mass of 230 - 250 g middot mol^-1. What is its molecular formula? (A) C_13 H_2 O_4 (B) C_14 H_1) O_4 (C) C_13 H_6 O_4 (D) C_12 H_14 O_3 Aluminum reacts with sulfur to form aluminum sulfide. If 31.9 g of AI are reacted with 72.2 g of S, what is the theoretical yield of aluminum sulifde in grams? (A) 88.8 g (B) 69.7 g (C) 57.2 g (D) 113 g According to EPA guideliness the permissible level for lead in drinking water is 15 parts per billion (ppb). What is the maximum allowable mass of lead that could be present in 1.00 L of H_2 O? (A) 0.015 ng (B) 0.015 mu g (C) 0.016 mg (D) 0.015 g Aqueous solutions of electrolytes that produce two ions upon ionization typically exhibit freezing point depressions that are twice as large as solutions of non-electrolytes with the same concentration. Which 0.10 M electrolyte solutions will show the smallest depression? (A) HCI (B) NaBr (C) JBI_3 (D) MgSO_4 Interferon is a water-soluble protein. A solution prepared by dissolving 15.0 mg of interferon in 2.50 mL of H_2O exhibits an osmotic pressure of 5.80 mm Hg at 25 degree C. What is the molar mass of interferon? (A) 1.92 times 10^4 g middot mol^-1 (B) 1.92 times 10^7 g middot mol^-1 (C) 1.95 times 10^5 g middot mol^-1 (D) 1.61 times 10^2 g middot mol^-1 Which noble gas is most abundant in the earth's atmosphere? (A) He (B) Ne (C) Ar (D) Rn Which of the acids below has the most ionizable hydrogen atoms per molecule? I. H_3 PO_4 II> H_3 PO_3 III> H_3 PO_2 (A) I only (B) II only (C) III only (D) Each one contains the same number of ionizable H atoms Aluminum is most often found in nature as the (A) carbonate. (B) chloride (C) oxide. (D) sulfide. According to the Tyndall Effect, a beam of light becomes visible when passed through all of the following except a(n). (A) aerosol. (B) colloid (C) emulsion. (D) solution. All of the following can be used as primary can be used as primary standards in acid-base titrations EXCEPT (A) oxalic acid. (B) potassium hydrogen phthalate. (C) sodium carbonate. (D) sodium hydroxide. Which of the graphs shown below would best represent the changes when 0.10 M barium hydroxide was titrated with 0.10 M sulfuric acid?Explanation / Answer
1)Answer is D.(16),coefficient for boron oxide is 2,for graphite it is 7,for boron carbide it is 1 & for carbon monoxide it is 6 altogether it is 16.
4)Answer is C)0.015mg in 1litre.
7)Answer is C)Argon,Of all the rare gases, argon is present in the greatest amount. It makes up about 0.9 percent by volume of Earth's atmosphere.
8)Answer is A)I only,because H3PO4 produces three ionisible hydrogen ions.
9)Answer is C)Oxide,aluminium mostly exists as aluminium oxide.
10)Answer is D)solution because it is not observed in solutions.
11)Answer is D)Sodium hydroxide because it absorbs moisture and carbon dioxide easily.
12)Answer is C,since Barium hydroxide is strong base and sulphuric acid is strong acid.
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