Chemistry: Post your doubts here!

[ZaqZainab]

Metanoia , ZaqZainab , @ Every One , Could u Plz help me with this
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s05_qp_1.pdf

Q2..Answer B
Q13.Answer B>>>Why it is not Mg ??Mg is just beside Al , so i thought that it will have a similar Electronegativity as Mg.
Q15.Answer C>>>When H2SO4 acts as an acid and when it acts as an oxidizing agent?
Q31.Answer A>>>I know that this is simple, but i am always confused with this type,So is there any hint??
Q32.Answer D
Q33.Answer B
Q40.Answer B

THNX in advance

Q2 find the moles of N2 when 1 mole of NaN3 is used
2:3 ratio so
3/2 of N2
and then Na is also made which makes further reaction take place
mole ratio for NaN3 and Na is
2:2
so 1 mole of NaN3 gives 1 mole of Na
this 1 mole Na reacts with KNO3 to give more N2
mole ration of Na and N2 in the second equation
10:1
so 1 mole of Na will give 1/10N2 so
1/10 + 3/2

Q3
look at the options (THE NUMBERS I USE ARE NOT ACTUAL THEY ARE JUST TO MAKE AN UNDERSTANDING)
A)Barium has very less electroneagtivity FROM Al it move 3 steps to decreasing (by moving down) and 2 more steps to decreasing by moving tot the left so diffrence 2+2=4 less
B) Magnesium moves just 1 step to the left ie 1 less
C)Beryllium moves 1 more (up) and 1 step back (by moving to the right) 1-1=0
D)....Use this way 1 back and 2 down 1+2=3 less

 

[ZaqZainab]

Pentanol, C5H11OH, has four structural isomers that are primary alcohols.
How many of these primary alcohols contain a chiral carbon atom?
A0
B1
C2
D3

anyone ? thanks in advance

B
CH3(CH2)4OH
CH2(CH3)(CH2)3OH
CH(CH3)2(CH2)2OH
C(CH3)3CH2OH

 

[loveyuan]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s05_qp_1.pdf

Q19, how is it nucleophillic substitution, i mean Br is an electrophile.

The O in the -OH group is more electronegative so it is partial negative while C is partial positive .
Br attack C which is partial positive so it is nucleophilic

 

[loveyuan]

Metanoia , ZaqZainab , @ Every One , Could u Plz help me with this
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s05_qp_1.pdf

Q2..Answer B
Q13.Answer B>>>Why it is not Mg ??Mg is just beside Al , so i thought that it will have a similar Electronegativity as Mg.
Q15.Answer C>>>When H2SO4 acts as an acid and when it acts as an oxidizing agent?
Q31.Answer A>>>I know that this is simple, but i am always confused with this type,So is there any hint??
Q32.Answer D
Q33.Answer B
Q40.Answer B

THNX in advance

Q31 : is it PH3 is trigonal planar ? i though it should be trigonal pyramidal ???

 

[doremon]

Pentanol, C5H11OH, has four structural isomers that are primary alcohols.
How many of these primary alcohols contain a chiral carbon atom?
A0
B1
C2
D3

anyone ? thanks in advance

the answer is 0. Draw the four isomers.

 

[loveyuan]

the answer is 0. Draw the four isomers.

the answer is 1 ~

 

[doremon]

the answer is 1 ~

woops it's 3-methylbutan-1-ol

 

[Snowysangel]

Is carboxylic acid completely soluble in water?

 

[Browny]

check it again.

 

[Browny]

Is carboxylic acid completely soluble in water?

Yes

 

[Snowysangel]

Also isn't alcl3 tetrahedral and not trigonal planar??

 

[randomcod]

I have learned it in another way and its a whole new concept but if you wanna know it i will explain my way it works everytime

yes please!

 

[Zepudee]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w06_qp_1.pdf

Q3 (C), 4 (D), 21 (C), 25 (B)

 

[Browny]

Also isn't alcl3 tetrahedral and not trigonal planar??

It is trigonal planar as it Al has only 3 outer electrons as it is in group 3 and those three are covalently bonded to Cl so it has only 3 bond pairs and is trigonal planar.

 

[Snowysangel]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s12_qp_12.pdf 33 answ is D

 

[Browny]

Can someone please look into these difficult questions?

 

[huh]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s13_qp_11.pdf

Help in q30 please. Cant differentiate between B and D.

 

[Browny]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s12_qp_12.pdf 33 answ is D

2 is wrong as it is not high as it is formed from a reversible reaction and 3 is wrong as HSO4- is formed from a one way reaction but as the other is formed from a reversible one.

 

[Snowysangel]

2 is wrong as it is not high as it is formed from a reversible reaction and 3 is wrong as HSO4- is formed from a one way reaction but as the other is formed from a reversible one.

So HSO4 will be greater than SO4...but won't that shift the equilibrium to the right?

 

[Browny]

Snowysangel can you check out my questions