dlxpxv7的部落格

標題:

• 我想問下!!!!!!!@1@
• 我很笨喔,求助!!
• Express √50 in terms of p

• 我想問下!!!!!!!@1@
• 我很笨喔,求助!!
• Express √50 in terms of p

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HKCEE CHEM 2007 MC 40

發問:

有沒有人識答?HKCEE CHEM 2007 MC #40?可唔可以解釋一下?

最佳解答:

First calculate the % by mass of C in CaCO3: 12.0 / 100.1 x 100% = 12.0% As there is an increase in volume of CO2 collected, the no. of moles of CO2 is greater. Thus the impurity must be a metallic carbonate with % by mass of C greater than 12.0%. For MgCO3, % by mass of C: 12.0 / 84.3 x 100% = 14.2% For ZnCO3, % by mass of C: 12.0 / 125.4 x 100% = 9.57% For FeCO3, % by mass of C: 12.0 / 115.8 x 100% = 10.4% For CuCO3, % by mass of C: 12.0 / 123.5 x 100% = 9.72% Hence A is the answer.

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