Chemistry: Post your doubts here!

[gary221]

In 37, the ans is B ie 1 n 2 r correct, bcoz cracking is the breakdown of large Alkanes to form useful smaller alkanes n alkenes..
so the defn fits only the 1st 2 pts, hence b is right..

 

[gary221]

They are not in the same period

oh, i get it...
v r supposed to cmpr the chlorine atoms only, nt the carbon atom at all...
n since in a sample of Cl isotopes r presnt, the only thng common amogst all the Cl atoms is thr radius ie same no. of shells...

 

[DPratik]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf
In Q34 why is statement 1 true?

sulphuric acid is a stronger acid which means it would dissociate fast so it would produce more gas than ethanoic acid in 2mins,if you balance the equation then you can see that 1 mole of sulphric acid produces 1 mole of hydrogen gas but 2 mole of ethanoic acid produces 1 mole of hydrogen gas which means with the reaction of ethanoic acid less hydrogen gas is formed as compared to suphhuric acid...but i don't have any exact reason for option number 1 !!!

 

[DPratik]

well this is a definition of lattice energy the energy change when 1 mole of (ionic)
solid/crystals is formed from its gaseous ions.
er mentions candidates lost mark for not specifying that a solid was formed......is it necessaryy......cant l.e be used for ionic liquids

hey what does ionic liquid look like ? never heard of it before....

 

[hassam]

http://en.wikipedia.org/wiki/Ionic_liquid

 

[DPratik]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s09_qp_1.pdf
Q11 Why cant answer be D
Q13 What to do in this?
Q31 How can radius be same?
Q34,Q35,Q37

for question 11) try balancing out the reaction,in option d) you may see on the left side total number of oxygen atoms is 108 but on the right side its just 18 so the answer D is obviously wrong !!

for question 13)as the question as stated Ca(OH)2 which is basic so look out for acid which means proton donor...you can see HCO3- as the only proton donor !!

for question 31) read the question carefully,it states that the relative mass of 12C is 12 and the relative mass of particular chlorine is 72,so the question has asked what properties of an atom is always the same,note that it hasn't asked the similar properties between that atom of chlorine and carbon but what properties of an atom with different mass number of the same element are same,so the answer is atomic radius because isotope has different nucleon number and different atomic mass but the same radius !!!

for question 34) the question has asked which statement classify's Bronsted-Lowry definition,though option 3 is also right but the definition of Bronsted Lowry only states that acids are proton donor ,it doesn't states whether a compound is basic or not !!!

for question 35) see the option 2 first,as CaCo3 and MgC03 can react with acids which means they can react with acid impurities and see the option 3) metal oxides can't be reduced to metals which means option 3 is wrong so the answer is option 1 and option 2 !!

for question 37) option 1 and option2 are right but option 3 ) is wrong because whats the use of inserting oxygen in hydrocarbon for fuels,never heard or read about it before !!!

 

[DPratik]

o

http://en.wikipedia.org/wiki/Ionic_liquid

thank you !!! now i heard of ionic liquid !!

 

[JD REBORN]

for question 11) try balancing out the reaction,in option d) you may see on the left side total number of oxygen atoms is 108 but on the right side its just 18 so the answer D is obviously wrong !!

for question 13)as the question as stated Ca(OH)2 which is basic so look out for acid which means proton donor...you can see HCO3- as the only proton donor !!

for question 31) read the question carefully,it states that the relative mass of 12C is 12 and the relative mass of particular chlorine is 72,so the question has asked what properties of an atom is always the same,note that it hasn't asked the similar properties between that atom of chlorine and carbon but what properties of an atom with different mass number of the same element are same,so the answer is atomic radius because isotope has different nucleon number and different atomic mass but the same radius !!!

for question 34) the question has asked which statement classify's Bronsted-Lowry definition,though option 3 is also right but the definition of Bronsted Lowry only states that acids are proton donor ,it doesn't states whether a compound is basic or not !!!

for question 35) see the option 2 first,as CaCo3 and MgC03 can react with acids which means they can react with acid impurities and see the option 3) metal oxides can't be reduced to metals which means option 3 is wrong so the answer is option 1 and option 2 !!

for question 37) option 1 and option2 are right but option 3 ) is wrong because whats the use of inserting oxygen in hydrocarbon for fuels,never heard or read about it before !!!

apart from Q37 all ur explanations are really not adequate...Plz someone explain to me

 

[USMAN Sheikh]

THIS ONE TOO PLSSSS ques no 2 and 5 only plsssssss be quick (((

pls do tell me

 

[gary221]

apart from Q37 all ur explanations are really not adequate...Plz someone explain to me

did u rd m cmnts??
n pls tell me if u gt thm

 

[JD REBORN]

did u rd m cmnts??
n pls tell me if u gt thm

yes i did but plz try to explain all of the questions

 

[gary221]

yes i did but plz try to explain all of the questions

well dude, its kind of hard...m nt a freakng genius here..
n it will help if u atleast acknowldge m replies, u know??

 

[JD REBORN]

well dude, its kind of hard...m nt a freakng genius here..
n it will help if u atleast acknowldge m replies, u know??

man sorry but if u say the wrong thing then how can i give u credit?If u give a good explanation i can only say thnx and like

 

[gary221]

well, if m sayng the wrong thng , i wud wnt u 2 correct me! v r all here 2 learn, n only thn can i cm upon d right ans [ like it hpnd abv]

 

[gary221]

So, r all ur doubts cleared now??

 

[JD REBORN]

So, r all ur doubts cleared now??

no i still posted the questions earlier

 

[USMAN Sheikh]

any one pls q 2 aand 5 pls be quick

 

[gary221]

pls do tell me

For 5, A n B dnt qualify, as nitrogen is bonded 2 only 2 atoms, so bond angles hv 2 b gr8r thn 109 or 104,
also since thr is a single lone pair (N) d bond angle cn nt b 180.
Which leaves only C as the ans...

 

[gary221]

no i still posted the questions earlier

ok, lets go thru thm 1 by 1.
Did u gt ques 11??

 

[JD REBORN]

ok, lets go thru thm 1 by 1.
Did u gt ques 11??

No I didint