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34 In each of the four solution shown below, a strip of Mg is added.Tube I: silver nitrate solution + MgTube II: lead(ll) nitrate solution + MgTube III: magnesium sulphate solution + MgTube IV: copper(II) sulphate solution + MgWhich of the following combinations is correct? Tube ... 顯示更多 34 In each of the four solution shown below, a strip of Mg is added. Tube I: silver nitrate solution + Mg Tube II: lead(ll) nitrate solution + Mg Tube III: magnesium sulphate solution + Mg Tube IV: copper(II) sulphate solution + Mg Which of the following combinations is correct? Tube Observation A I Grey coating on Mg B II Brown coating on Mg C III Bubbles are give off D IV Grey coating on Mg 35 Metal X reacts with hot water more readily than metal Y does. Which of the following statements are probably correct? 1 X displaces Y from the solution of nitrate of Y 2 It is more difficult to reduce the oxide of X when compared to the oxide of Y 3 Both X and Y react with steam to form hydroxides A 1 2 B 1 3 C 2 3 D 1 2 3 Question 36 refer to the results of experiments for three metals X, Y and Z, and their compounds. Metal Reaction with cold water Action of heat on metal oxide X No reaction No reaction Y Hydrogen liberated No reaction Z No reaction Metal and oxygen formed 36 The descending order of reactivity of the three metals is A X,Y,Z B X,Z,Y C Y,X,Z D Y,Z,X 37 The formula of ozone is O3. If 1 mole of ozone contains y atoms, how many atoms will 2 moles of oxygen gas contain? A 2y/3 B y C 4y/3 D 4y 38 Plaster of Paris is used for setting broken limbs. Its formula is CaSO4。1/2H2O. When water is added, it sets to give gypsum, CaSO4。2H2O. What is the minimum mass of water needed to set 0.500kg of plaster of Paris? A 62.0kg B 93.0kg C 124g D 290g 39 A silver coin, with a mass of 12.0g, was dissolved completely in concentrated nitric acid to give silver nitrate solution. When excess potassium chloride solution was added to the resulting solution, 14.4g of a white ppt were obtained. What is the percentage by mass of silver in the coins? A 45.5% B 60.0% C 75.0% D 90.0% 更新: 40 The formula of hydrated sodium carbonate crystals is Na2CO3。XH2O. When 66.9g of the hydrated crystals are heated, 24.8g of anhydrous sodium catbonate are produced. What is the value ofx? A 3 B 5 C 7 D 10

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34 A正確活潑性高的鎂成功置換銀銀是灰色的 B不正確活潑性高的鎂雖成功置換鉛,但鉛是灰色的,不是棕色的 C不正確鎂和溶液沒有反應,而這置換反應不會生成氣體 D不正確活潑性高的鎂雖成功置換銅,但銅是棕色的,不是灰色的 所以答案是A 35 1正確,容易與熱水反應表示活潑性較高,所以可以置換 2正確,活潑性越高,代表越難分解 3正確,可以與熱水反應,證明可以與反應性更高的水蒸氣反應 答案是D1,2,3都正確 36 活潑性高的金屬才可以與水反應,所以Y活潑性最高 活潑性越高提取方法越難,熱分解為較不活潑金屬氧化物的提取方法 X氧化物不能用熱分解提取,而Z可以 證明X的活潑性高於Z 所以Y>X>Z 答案是C 37 1摩爾的O3有Y個原子設L為亞佛加得羅常數 原子粒子數目=摩爾數x粒子數xL 1x3xL=Y---1 設2摩爾的O2有X個原子 2x2xL=X---2 把2式除以1式 得出X=Y(4)/3 所以答案是C 38 Ca的摩爾質量=40.1S的摩爾質量=32.1O的摩爾質量=16 H的摩爾質量=1 CaSO4.1/2H2O+3/2H2O生成CaSO4.2H2O 從方程CaSO4.1/2H2O和3/2H2O1:3/2 0.500kgx1000=500g CaSO4.1/2H2O摩爾質量=(40.1+32.1+16X4+0.5X18)=145.2 H2O的摩爾質量=18 CaSO4.1/2H2O摩爾數=500/145.2=3.44mol 水的質量=3.44x3/2x18=92.9g 所以答案B應該是92.9g吧 所以答案是B 39 反應的方程式 Ag+2HNO3生成AgNO3+NO2+H2O KCl(aq)+AgNO3(aq)生成AgCl(s)+KNO3(aq)把這方程寫成離子方程 Cl-+Ag+生成AgCl 銀摩爾質量:107.9氯的摩爾質量=35.5 AgCl:AgNO3摩爾比1:1 AgNO3:Ag摩爾比1:1 所以AgCl摩爾數=Ag摩爾數 AgCl摩爾數=14.4/143.4=0.100mol 銀的質量=0.1x107.9=10.8g 銀質量百分比=10.8/12x100%=90.3% 所以答案是D 40 反應的方程式 Na2CO3.XH2O生成Na2CO3+XH2O Na摩爾質量=23C的摩爾質量=12O的摩爾質量=16 H的摩爾質量=2 方程中Na2CO3.XH2O和Na2CO3的摩爾比1:1 Na2CO3.XH2O的摩爾數=Na2CO3的摩爾數 66.9/23x2+12+16x3+18x=24.8/23x2+12+16x3 66.9/106+18x=24.8/106 66.9=0.234(106+18x) 66.9=24.8+4.21x 42.1=4.21x x=10 答案是D 2010-02-08 18:13:35 補充: 多謝幫手=..= 本人是讀中文的 還以為哪是解氫氣 2010-02-08 18:18:03 補充: 修正 35的答案是A只有1,2正確,雖然它們和水蒸氣有反應 可是只會形成氧化物,而不會形成氫氧化物

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35 . 1 X displaces Y from the solution of nitrate of Y 2 It is more difficult to reduce the oxide of X when compared to the oxide of Y 3 Both X and Y react with steam to form hydroxides 第3個 Metal react with steam 係form Metal Oxide 而唔係 Hydroxides 第3個錯 A 先真呀
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