Biology; Chemistry; Physics: Post your doubts here!

[luckywang]

1 = A
14= D
20= D
36 = B...

why 20 is D? i tot muscle wont produce CO2 and only convert glucose to lactic acid with a little amount of energy? it stated 'occur first', then the answer is B? if no enough oxygen and how the concentration of CO2 in blood increase? breathing rate have to increase in order to increase oxygen intake to break down glucose to CO2 and the concentration of CO2 in blood will only increase?

 

[Tharindu]

cobalt chloride is blue? since it is test for water present and change to pink? or blue colour is incomplete and after water added then only the reaction is completed and the final colour is pink?

Sorry I forgot to mention that these are colours of hydrated salts....

 

[falcon678]

is lead(II) nitrate an acid or it is a salt? only compound with hydrogen like sulphuric and nitrate only consider as an acid?

dude its a salt.....for a compound to be acid it shld ve hydrgn in it n it shld be dissipatd whn in aqueous form...!!

cobalt chloride is blue? since it is test for water present and change to pink? or blue colour is incomplete and after water added then only the reaction is completed and the final colour is pink?

yess copr chloride is blue...it chnges to pink AFTR coming in contact with water...!! n blue is its original n complete colour..!!

 

[Tharindu]

cobalt chloride is blue? since it is test for water present and change to pink? or blue colour is incomplete and after water added then only the reaction is completed and the final colour is pink?

Sorry my bad....I forgot to mention tat

 

[luckywang]

Sorry I forgot to mention that these are colours of hydrated salts....

oh...

 

[Tharindu]

oh...

Btw...are others correct for anyhydeous also????

 

[luckywang]

dude its a salt.....for a compound to be acid it shld ve hydrgn in it n it shld be dissipatd whn in aqueous form...!!



yess copr chloride is blue...it chnges to pink AFTR coming in contact with water...!! n blue is its original n complete colour..!!

erm... salt contain water? so salt with water is the completed reaction or salt without water?

 

[falcon678]

salt with watr is in crystal form n without watr is anyhydrous......it has no link with reaction...it just depends whetr u ve evaprtd to dryness the salt durin crystalisation or not...

 

[luckywang]

Btw...are others correct for anyhydeous also????

i not sure about the colour too.... in my school exam only ask colour of those common metal like Mg, Ca, Cu and Na.... the most common one is copper(II)... which is blue in ion...

 

[luckywang]

salt with watr is in crystal form n without watr is anyhydrous......it has no link with reaction...it just depends whetr u ve evaprtd to dryness the salt durin crystalisation or not...

oh... got it...

 

[falcon678]

oh... got it...

 

[luckywang]

ask one more question... salt produced in neutralisation is anhydrous salt or hydrous salt? like, NaOH + HCl -> NaCl + H2O... is anhydrous salt right? coz H20 is produced and the salt is only NaCl but not NaCl.xH2O?..

 

[snowbrood]

can anyone solve S08_ QP_2 A2(c)?? the ionic equation one

 

[luckywang]

can anyone solve S08_ QP_2 A2(c)?? the ionic equation one

Fe2+ -> Fe3+?

 

[luckywang]

Is the periodic table and qualitative notes provided in chemistry paper 1,2 and 4? i only knew qualitative notes are not provided in paper 4 since it already written in the syallbus... but how about paper 1 and 2?

 

[snowbrood]

Fe2+ -> Fe3+?

 

[snowbrood]

Fe2+ -> Fe3+?

why do they balance by 4 (both iron ions)

 

[falcon678]

ask one more question... salt produced in neutralisation is anhydrous salt or hydrous salt? like, NaOH + HCl -> NaCl + H2O... is anhydrous salt right? coz H20 is produced and the salt is only NaCl but not NaCl.xH2O?..

dude the salt producd is in aqueous form.......u ve to extrct it by crystalisation.....!!

 

[falcon678]

Is the periodic table and qualitative notes provided in chemistry paper 1,2 and 4? i only knew qualitative notes are not provided in paper 4 since it already written in the syallbus... but how about paper 1 and 2?

qualitative notes r only for paper 3.......not for any othr papr...!!! howeva periodic table will be providd in papr 1 n 2...!!

 

[SilverCrest]

What is the purpose of carbon brushes?