[化學] 請教一些化學問題
1.Compound 1 has a composition of 46.7mass% of element A
and 53.3 mass% of element B.
A and B also form a second binary compound(compound 2).
If the compositions of the two compounds are consistent with
the law of multiple proportions,
which of the following compositions compositions could be that of compound 2?
A)23.4 mass %A 76.6 mass %B
B)30.4 mass %A 69.6 mass %B
C)33.3 mass %A 66.7 mass %B
D)53.3 mass %A 46.7 mass %B
E)73.3 mass %A 26.7 mass %B
答案：(B)
2.The amount of calcium present in milk can be determined
by adding oxalate to a sample and measuring the mass of calcium oxalate
precipitated.
What is the mass percent of calcium if 0.429g of calcium oxalate forms
in a 125-g sample of milk when excess aqueous sodium oxalate is added?
Na2C2O4(aq)+ Ca2+ (aq)→CaC2O4(s)+2Na+(aq)
A) 0.107%
B) 0.202%
C) 0.343%
D) 1.10 %
E) 1.37 %
答案：(A)
3.Mineral oil can be used in place of mercury in manometers
when small pressure changes are to be measured.
When is the pressure of an oxygen sample in mm of mineral oil
if its pressure is 28.5 mmHg?(d of mineral oil =0.88 g/mL, d of Hg=13.5g/mL)
A)1.9 mm mineral oil
B)15 mm mineral oil
C)32 mm mineral oil
D)380 mm mineral oil
E)440 mm mineral oil
答案：(E)
不好意思 這三題= =
我看完題目就不知道該怎麼下手做 ...這樣
不知道可否請大家指點一下
謝謝~
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 120.97.75.2
推
04/17 22:07, , 1F
04/17 22:07, 1F
→
04/19 19:33, , 2F
04/19 19:33, 2F
討論串 (同標題文章)