Biology; Chemistry; Physics: Post your doubts here!

[AhsanAfzal]

plz i need imran merchant chemistry guess paper of paper 1 and 2

me 2 pls

 

[ayesha121997]

14 Which reaction does not involve either oxidation or reduction?
A CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
B Cu2+(aq) + Zn(s) → Cu(s) + Zn2+(aq)
C CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l)
D Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g)
answer is c explain me,.....

 

[asma tareen]

me 2 pls

tag me if u got it

 

[asma tareen]

14 Which reaction does not involve either oxidation or reduction?
A CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
B Cu2+(aq) + Zn(s) → Cu(s) + Zn2+(aq)
C CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l)
D Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g)
answer is c explain me,.....

C cux in neutralization reaction oxidation states of the reactants and products are same

 

[Young Stunner]

How would you draw copper. Please help?

 

[sohaib Ahmes]

well he is right...

its considered to be concentrated..

please post imran merchant chemistry guess paper of mcq and theory!!!!!!!!!

 

[Young Stunner]

How would you draw copper. Please help?

Like this?

 

[asma tareen]

Like this?

i think u should have also drawn the sea of electrons

 

[Young Stunner]

i think u should have also drawn the sea of electrons

Is it fine now?

 

[asma tareen]

Is it fine now?

i think so

 

[Young Stunner]

i think so

OK Thankyou

 

[chocolate_girl]

Do we get a break between two papers??

 

[HarithAslam]

Do we get a break between two papers??

yep, maybe 10 mins or so

 

[TheStallion-Reborn]

http://papers.xtremepapers.com/CIE/...al O Level/Chemistry (5070)/5070_s08_qp_1.pdf
can someone please EXPLAIN the answers to question 1,10,26,35,38..

 

[AhsanAfzal]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s08_qp_1.pdf
can someone please EXPLAIN the answers to question 1,10,26,35,38..

i did this paper today. it was the hardest paper i hve ever seen! got 32/40!

 

[Kamihus]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s08_qp_1.pdf
can someone please EXPLAIN the answers to question 1,10,26,35,38..

1-The oxygen gas was collected by the displacement of water and was always going to be contaminated with water. Prior to the addition of hydrogen peroxide the apparatus was full of air which is approximately 80% nitrogen.
10-Pb(NO3)2 is only soluble compound shown other than H2SO4
26-Replace Se with S
Only SO2 and SO3 are correct. NaS is incorrect as Sulfur does not have a valency of 1. SO4 also has a valency of 2
35-In condensation polymerisation, water molecules are made along with the polymer
38-Four atoms and thus two molecules are needed to saturate the compound.

 

[AhsanAfzal]

answer Q32, Q34

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s08_qp_1.pdf​

kamihus

 

[TheStallion-Reborn]

1-The oxygen gas was collected by the displacement of water and was always going to be contaminated with water. Prior to the addition of hydrogen peroxide the apparatus was full of air which is approximately 80% nitrogen.
10-Pb(NO3)2 is only soluble compound shown other than H2SO4
26-Replace Se with S
Only SO2 and SO3 are correct. NaS is incorrect as Sulfur does not have a valency of 1. SO4 also has a valency of 2
35-In condensation polymerisation, water molecules are made along with the polymer
38-Four atoms and thus two molecules are needed to saturate the compound.

aaaryt....thnku!

 

[ayesha121997]

me 2 pls

me 2..

 

[ayesha121997]

38 A 10cm3 sample of a gaseous hydrocarbon is completely burnt in oxygen. The total volume of the products is 70cm3. All gas volumes are measured at room temperature and pressure.
Which equation represents the combustion of the hydrocarbon?
A CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
B C2H4(g) + 3O2(g) → 2CO2(g) + 2H2O(g)
C C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g)
D 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(g)
answer is b
how??? explain me plz...