a few mc questions(15marks)－hzb53jl55v的部落格

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a few mc questions(15marks)

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please give me the correct answers with steps/explainations1)Which of the following statements concerning household bleach is INCORRECT?A. The active ingredient of it is sodium hypochloriteB. Household bleach is produced by dissolving chloring in waterC. Household bleach can be used as disinfectantD.... 顯示更多 please give me the correct answers with steps/explainations 1)Which of the following statements concerning household bleach is INCORRECT? A. The active ingredient of it is sodium hypochlorite B. Household bleach is produced by dissolving chloring in water C. Household bleach can be used as disinfectant D. The raw material for manufacturing it is sodium chloride 2)In an experiment,43.6g of zinc was treated with 375cm3 of 1M hydrocloric acid.What is the volume of hydrogen was liberated at room temperature and pressure? (Relative atomic mass:Zn=65.4;molar volume of gas:24dm3) A. 4.5dm3 B. 6.0dm3 C. 7.5dm3 D. 9.0dm3

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Q1.The answer is B For A, This is correct.Household bleach contains hypochlorite ion(OCl-) which is the active ingredient of it since it can decolorize a dye by oxidation. OCl-(aq) + [dye] → Cl-(aq) + [dye+O] For B, This is incorrect since household bleach is produced by mixing Cl2(g) & cold dilute NaOH(aq).It is a mixture of water, sodium chloride & sodium hypochlorite. Cl2(g) + 2NaOH(aq) → NaCl(aq) + NaOCl(aq) + H2O(l) For C, This is correct.Household bleach can be used as disinfectant as it contains hypochlorite ions which can kill bacteria by giving free oxygen atom OCl-(aq) → Cl-(aq) + [O] For D, This is correct since household bleach is produced by mixing Cl2(g) & cold dilute NaOH(aq). Q2.The answer is A Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) No. of mole of Zn =43.6/65.4 =0.667mol No. of mole of HCl =(375/1000)(1) =0.375mol From the equation, the mole ratio of Zn and HCl is 1:2 Therefore, 0.1875mol(=0.375/2) of Zn is enough for the reaction. HCl is the limited reagent. No. of mole of H2 = No. of mole of HCl /2 = 0.375/2 =0.1875mol Volume of hydrogen liberated =0.1875 x 24 =4.5dm3

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