biology multiple choice

小霞的fans

A.

O.N. of Cr in L.H.S. = -2+8 = +6
O.N. of Cr in R.H.S. = (-2+14)/2 = +6
O.N. of H in both sides = +1
=> B,C,D are wrong.

[CrO4]2- is yellow while [Cr2O7]2- is orange. => A.
unlock-YM 發表於 5/3/2010 08:21 PM

                               
登錄/註冊後可看大圖

謝謝你^^唔介意我問多一題><""

Element X forms two oxides,XO2and XO3. if 1 mole of XO2contains n atoms,3 moles of XO3would contain

A.3n atoms
B.4n atoms
C.5n atoms
D.6n atoms

佢地既mole數唔一樣!??

unlock-YM

謝謝你^^唔介意我問多一題>
小霞的fans 發表於 6/3/2010 07:58 PM

                               
登錄/註冊後可看大圖

n x 4/3 x 3 = 4n atoms?

Mole數係唔一樣...

小霞的fans

n x 4/3 x 3 = 4n atoms?

Mole數係唔一樣...
unlock-YM 發表於 6/3/2010 12:21 AM

                               
登錄/註冊後可看大圖

係4n呀..

但係x4/3 x3 呢舊野點黎架@@?

unlock-YM

係4n呀..

但係x4/3 x3 呢舊野點黎架@@?
小霞的fans 發表於 7/3/2010 12:07 AM

                               
登錄/註冊後可看大圖

先當大家都係1 mole，咁XO3的atom數就係XO2的4/3。
佢話3 moles，咁再乘三就係答案。

小霞的fans

先當大家都係1 mole，咁XO3的atom數就係XO2的4/3。
佢話3 moles，咁再乘三就係答案。
unlock-YM 發表於 6/3/2010 04:12 AM

                               
登錄/註冊後可看大圖

3是因為XO3有3個Atoms嗎??4是XO4有4粒atoms嗎??

又發現問題>< ""

one mole of sulphur atoms has a mass twice that of one mole of oxygen atoms.which of the following statement(s) is/are correct ?

2. 2g of sulphur and 1g of oxygen each contain the same number of atoms
點解呢句錯既!?佢地既atom數量唔係都係=(mole x avogadro constant)1x6.02x10^23 咁多架咩???

鴨

oxygen is present in O2 under normal condition, but sulphur is S
so the no of mole of S is 2/32 while O is 1/32...

unlock-YM

oxygen is present in O2 under normal condition, but sulphur is S
so the no of mole of S is 2/32 while O is 1/32...
RX78-2 發表於 7/3/2010 05:16 PM

                               
登錄/註冊後可看大圖

但咁樣只係話1g oxygen有1/32 moles of O2，但number of atoms仍然係L/16...

鴨

喔
看錯了molecules
atoms的確是一樣的zzz

fish

one mole of sulphur atoms has a mass twice that of one mole of oxygen atoms.which of the following statement(s) is/are correct ?

2. 2g of sulphur and 1g of oxygen each contain the same number of atoms
點解呢句錯既!?佢地既atom數量唔係都係=(mole x avogadro constant)1x6.02x10^23 咁多架咩???
小霞的fans 發表於 7/3/2010 14:40

                               
登錄/註冊後可看大圖

97年第34條...?
如果是的話它的答案是B. (2) only, 亦即是指這statement 是對的

幻藍

97年第34條...?

fish 發表於 8/3/2010 01:34 AM

                               
登錄/註冊後可看大圖

完全沒有可以吐槽的空間