Chemistry: Post your doubts here!

[Browny]

Please help!!!!

 

[ZaqZainab]

One hydrogen in place of carbon

then it becomes secondary and so it can be oxidized

 

[SIstudy]

Please help!!!!

Ans fr Q3 is C?

 

[Zepudee]

GUYSSSS. Gotta help me with this, PLEASEEE. hahahaha
Must be very easy for you guys!
Anyways, okay.
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_13.pdf
Q27 (C)

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_12.pdf
Q3 (B) Q8 (D) [ i guess all these answers correctly, but i dont understand why ]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_qp_12.pdf
Q11 (A) [srsly no, what is this.]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_12.pdf
Q24 (B) , Q26 (A), Q30 (A)

THANK YOU SO SO MUCHHHHHH!! please help

 

[SIstudy]

GUYSSSS. Gotta help me with this, PLEASEEE. hahahaha
Must be very easy for you guys!
Anyways, okay.
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_13.pdf
Q27 (C)

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_12.pdf
Q3 (B) Q8 (D) [ i guess all these answers correctly, but i dont understand why ]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_qp_12.pdf
Q11 (A) [srsly no, what is this.]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_12.pdf
Q24 (B) , Q26 (A), Q30 (A)

THANK YOU SO SO MUCHHHHHH!! please help

See for Q11
the equation should be kinda balanced
as in there is 1X in both reactant and product
while Y is only n in both sides
just take it as a normal eqation like Br2 -> 2Br- (n is the 2 here)
I hope yu get it

 

[2moora]

why is the answer D in Q7 s12 variant 2 ??

 

[Hijab]

Can someone plz plz plz answer this question...

 

[chishtyguy]

Which substance, in 1 mol dm–3 aqueous solution, would have the same hydrogen ion
concentration as 1 moldm
3 of hydrochloric acid?
A ethanoic acid
B nitric acid
C sodium hydroxide
D sulphuric acid

Answer is B. But the question is....WHY?

nitric acid HNO3 will dissociate into H+ +NO3-, just like HCL
Ethanoic hardly dissociates
NaOH is a base
When H2SO4 dissociates it gives 2 H+ ions.

 

[chishtyguy]

CH3CO2CH3 is behaving in the same way as the HCN was behaving with aldehyde
So when you work it out you'll know why the answer is C not B

Yr plz explain the structure... Aldehyde in C is Propanal and in B is ethanal... So why Its not B??

 

[Ahmed Aqdam]

hey i found u here too
can u help me with question 40 in this paper
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s13_qp_12.pdf

In statement 1, 2 moles of ethanoic acid will react with 1 mole of calcium ion as charge on calcium is +2. So compound will be Ca(CH3CO2)2 which has empirical formula CaC4H6O4.
In 2 and 3, both H from CO2H will be removed so empirical formula will be CaC4H4O4 and not CaC4H6O4.

 

[asfand798]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s08_qp_1.pdf

Guys please help me!
Q.8,10,18,21,27,28,29,30,32,33,34

 

[sudeep1097]

GUYSSSS. Gotta help me with this, PLEASEEE. hahahaha
Must be very easy for you guys!
Anyways, okay.
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_13.pdf
Q27 (C)

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_12.pdf
Q3 (B) Q8 (D) [ i guess all these answers correctly, but i dont understand why ]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_qp_12.pdf
Q11 (A) [srsly no, what is this.]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_12.pdf
Q24 (B) , Q26 (A), Q30 (A)

THANK YOU SO SO MUCHHHHHH!! please help

3 is B just use stoichiometric ratios 1 mole IO3 reacts with 2 mole cl while 1 mole I2 reacts with 4 mole cl which is like 1 mole I2 reacting with 2 mole Io3 that is 1:2 ratio
I would like help with 8 D too

 

[SIstudy]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s12_qp_11.pdf
Q23 ?? :/ (ANS - B)
I don't really get the compound C drawn :S

 

[papajohn]

Q28 C how??
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s13_qp_13.pdf

 

[Browny]

Ans fr Q3 is C?

Yes.

 

[SIstudy]

Yes.

Well yu see at the first glimpse of the question yu should make out tht D is incorrect as the Cs and Na is in same group
the charges wont also affect since Cs and Na hav the same charge
the only thing tht is valid is tht Cs is quite a large sized atom, comparatively so the Ionic radius should be the ans

 

[sudeep1097]

Please guys help especially with 5. For 26 ans is D but B also forms secondary carbocation and it could be stable as well like in sn2 mechanisms so why it isn't B?

 

[Asad rehman]

for Q 21 it is B
For Q 26 its D because it is tertiary and opens to only SN1 reaction whose rate only depends on conc. of Halogenoalkane
For Q 25 Cl atom can replace any H on carbon atom so it can replace 4 atoms anyone at a time
Hope this helps

 

[GCE As and a level]

Please guys help especially with 5. For 26 ans is D but B also forms secondary carbocation and it could be stable as well like in sn2 mechanisms so why it isn't B?

View attachment 45107 View attachment 45108 View attachment 45109 View attachment 45110

For Q5,The answer is B
This Question is simple,but tricky
Lsn...The Enthalpy change to convert I2 from solid to gas is +38 KJ mol^-1 (GIVEN)
The Enthalpy change for the reaction of I2(g) with Cl2 is -214 KJ mol^-1 (GIVEN)
Wat is the definition of enthalpy change of formation of ICl3?? it is when i mol of a ICl3 is produced from its elements
The enthalpy change for the production of 2ICl3 is = +38 - 214 = -176 KJ mol^-1
2 ICl3 --------> - 176
1 ICl3 --------> -176 /2 = - 88 KJ mol^-1

Hope this helps

 

[GCE As and a level]

Please guys help especially with 5. For 26 ans is D but B also forms secondary carbocation and it could be stable as well like in sn2 mechanisms so why it isn't B?

View attachment 45107 View attachment 45108 View attachment 45109 View attachment 45110

MAn could u plz include the answers next time
BEST OF LUCK