Chemistry MCQ thread...

[sibtain1227]

http://www.xtremepapers.me/CIE/Internat ... 3_qp_1.pdf


q10 !!!
and kindly explain ur choice !

 

[xHazeMx]

See the attachment.

that was really helpful

 

[xHazeMx]

http://www.xtremepapers.me/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_s03_qp_1.pdf


q10 !!!
and kindly explain ur choice !

0.26 moles formed from H and I so 0.26/2 = 0.13
moles at equlibrium :
H : 0.20 - 0.13 = 0.07
I : 0.15 - 0.13 = 0.02
and HI has 0.26 moles
so the Kc would be [0.26]^2/[0.07][0.02]
so the answer is C

 

[Zishi]

http://www.xtremepapers.me/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_s03_qp_1.pdf


q10 !!!
and kindly explain ur choice !

It's C.

0.26 moles of HI are formed from 0.13 moles of each of the reactants(according to the balanced equation).

Remaining moles of H2= 0.20-0.13 = 0.07 OF I2 = 0.15-0.13=0.02

Put all of 'em in expression of Kc, you'll get C as the answer.

 

[kakarocks]

Anyone of you done mj 2010 p11 it's pretty dodgy . just did it for the first time and got 25/40 and i am supposed to be good in chemistry , especially As since i also gave A2 :S

 

[kakarocks]

Reasons behind MJ 2010 p 12 q 25 and q26 anyone?

 

[Zishi]

Reasons behind MJ 2010 p 12 q 25 and q26 anyone?

For 25: Remove the hydrogen free radicals from all the carbon atoms in turns, and check how many different structures you get. You'll get 3.

For 26: D is the answer because it is an Sn1 reaction which depends on the concentration of alkyl halides. So changing the conc of hydroxide ions won't affect the rate of reaction.

 

[Anonymousx3]

I'm not entirely sure about this, but I just wanted to make sure.
The different forms of X` are:

R-CH2`
R-CHCl`
R-CCl2`

 

[xHazeMx]

explain ur choice

 

[xHazeMx]

I'm not entirely sure about this, but I just wanted to make sure.
The different forms of X` are:

R-CH2`
R-CHCl`
R-CCl2`

C right ?

 

[Anonymousx3]

explain ur choice

The answer's D, right?
I'd explain but it's kinda difficult to type cis-trans isomers.. :X

 

[Anonymousx3]

I'm not entirely sure about this, but I just wanted to make sure.
The different forms of X` are:

R-CH2`
R-CHCl`
R-CCl2`

C right ?

Yeah, it's C.
But are those 3 forms of X` correct?

 

[xHazeMx]

yeah its correct

 

[xHazeMx]

explain ur choice

The answer's D, right?
I'd explain but it's kinda difficult to type cis-trans isomers.. :X

no problem i m just getting 6 not 7, i will solve it again

 

[Anonymousx3]

The 7 isomers of C3H4Cl2 :

1. CH3CH=CCl2

2 & 3. CH3Cl=CHCl (this has a -cis and a -trans form)

4. CH2ClCCl=CH2

5 & 6. CH2Cl=CHCl (this also has a -cis and a -trans form)

7. CHCl2CH=CH2


I hope that made sense.

 

[kakarocks]

I'm not entirely sure about this, but I just wanted to make sure.
The different forms of X` are:

R-CH2`
R-CHCl`
R-CCl2`

C right ?

Yeah, it's C.
But are those 3 forms of X` correct?

I dont get it shouldn't it be R-Ch2cl Chcl2 ccl3

 

[Anonymousx3]

No, what you wrote aren't free radicals.
The question is asking about the different forms of X` produced.

 

[xHazeMx]

The 7 isomers of C3H4Cl2 :

1. CH3CH=CCl2

2 & 3. CH3Cl=CHCl (this has a -cis and a -trans form)

4. CH2ClCCl=CH2

5 & 6. CH2Cl=CHCl (this also has a -cis and a -trans form)

7. CHCl2CH=CH2


I hope that made sense.

check 5 & 6 there is one extra hydrogen atom, thx anyways

 

[kakarocks]

No, what you wrote aren't free radicals.
The question is asking about the different forms of X` produced.

Oh yeh free radicals ..... so so your'e right thankyou sir

 

[Anonymousx3]

The 7 isomers of C3H4Cl2 :

1. CH3CH=CCl2

2 & 3. CH3Cl=CHCl (this has a -cis and a -trans form)

4. CH2ClCCl=CH2

5 & 6. CH2Cl=CHCl (this also has a -cis and a -trans form)

7. CHCl2CH=CH2


I hope that made sense.

check 5 & 6 there is one extra hydrogen atom, thx anyways

Oops, I typed it wrong.
CH2ClCH=CHCl