Chemistry MCQ thread...

[Anonymousx3]

please please please answer this and explian your working

Is it C?
If my answer's correct, I'll explain it.

 

[Mobeen]

@saturation . ill look for 5 in the past papers and let u know ..

 

[Saturation]

please please please answer this and explian your working

Is it C?
If my answer's correct, I'll explain it.

Isn't it C4H8?? What's the answer!

@saturation . ill look for 5 in the past papers and let u know ..

yeah, thanks alot, btw for the 4th qs, what are the 3 alkenes!?

 

[abdullah181994]

@ anonymosx i also answered it c but the correct answer is D.

 

[Mobeen]

@saturation
ur q1 is june 2010 qp11 q22 and answer from mark scheme is B

 

[Mobeen]

@Saturation
ur q2 is june 2010 qp11 q24 and answer in marks scheme is C
ur q3 is june 2010 qp11 q28 and answer " " " is D
ur q4 is june 2010 qp11 q29 and answer " " " is B

 

[Anonymousx3]

@ anonymosx i also answered it c but the correct answer is D.

k.
I'm not completely sure, but maybe this is why:

You get 0.8 mol of both carbon dioxide and water. So the equation will look something like this:

0.2CXHY + 02 ----> 0.8CO2 + 0.8H20

So, to get 0.8 carbons, X needs to be 4 (0.2 X 4). And to get 1.6 hydrogens Y needs to be 8 (0.2 X 6).

Which means the answer is D - C4H8.

I hope that makes sense. If not, let me know and I'll try explaining again.

 

[Saturation]

@ anonymosx i also answered it c but the correct answer is D.

It's C4H8, :

0.2 mol produced 35.2g of CO2 and 14.4g of H20, which is 0.8 mol of CO2 and 0.8mol of H20

so now you have the ratio, 0.2 gave us 0.8, so 1 mol should give us 4 mol each. Now we have the balanced equation, so just adjust the number of carbon and hydrogen, to match equation:

CxHy + 6O2 = 4CO2 + 4H20

therefore, x = 4 and y = 8, so it's C4H8!

 

[Mobeen]

*for q4 is B ^

 

[Saturation]

*for q4 is B ^

Thanks, but can you tell me what the 3 alkenes are!?

 

[Anonymousx3]

@ anonymosx i also answered it c but the correct answer is D.

It's C4H8, :

0.2 mol produced 35.2g of CO2 and 14.4g of H20, which is 0.8 mol of CO2 and 0.8mol of H20

so now you have the ratio, 0.2 gave us 0.8, so 1 mol should give us 4 mol each. Now we have the balanced equation, so just adjust the number of carbon and hydrogen, to match equation:

CxHy + 6O2 = 4CO2 + 4H20

therefore, x = 4 and y = 8, so it's C4H8!

Yeah, I got it. ;p
Thanks.

 

[Mobeen]

@saturation my answers were correct and now u can even check them from mark scheme

 

[abdullah181994]

thanks@ saturation

 

[Saturation]

@saturation my answers were correct and now u can even check them from mark scheme

I know, but what about qs 5!? and what are the 3 alkenes for qs 4 pls! Thanks!

 

[Mobeen]

*for q4 is B ^

Thanks, but can you tell me what the 3 alkenes are!?

i dont know it either .. only know it because ive seen this question in past papers 2 or 3 times.. atleast now ur sure abt the answer because the marking scheme says so

 

[Mobeen]

@saturation my answers were correct and now u can even check them from mark scheme

I know, but what about qs 5!? and what are the 3 alkenes for qs 4 pls! Thanks!

ill search for q5 too ..

 

[Saturation]

thanks@ saturation

welcome!

*for q4 is B ^

Thanks, but can you tell me what the 3 alkenes are!?

i dont know it either .. only know it because ive seen this question in past papers 2 or 3 times.. atleast now ur sure abt the answer because the marking scheme says so

haha , ok then, and yeah the qs do repeat! btw please let me know if you find qs 5! Thanks!

 

[Mobeen]

saturation u were right .. q5 is D .. it is w08 qp1 q 38 . answer is D ..

 

[abdullah181994]

Some one please explian why graphite is more stable then diamond.

 

[Saturation]

saturation u were right .. q5 is D .. it is w08 qp1 q 38 . answer is D ..

phew! so what I said earlier makes sense then? It's chloro flouro carbons which are used in extinguishers? (and btw some of the HALOGENOALKANES are extremely flammable!)

Some one please explian why graphite is more stable then diamond.

There was an entire disscussion about this earlier in this thread or in the another one. Here's what I remember: diamond to graphite is an exothermic reation, which means the products have less energy, so therefore they are more stable!