Chemistry: Post your doubts here!

[The Sarcastic Retard]

ohkay so u tried each of the options?

No, I first balanced Al and Na. Then I balanced O, then I saw there are 3 atoms of carbon present, so I knew that option A or C can come I saw option C, H molecules were not balancing so I tried with A.

 

[forest822]

For 2, why C is not the answer? Usually PV=constant right?

 

[The Sarcastic Retard]

View attachment 57472For 2, why C is not the answer? Usually PV=constant right?View attachment 57473

2) At constant temprature, Pv is proportional to n.
15) Answer is B?

 

[donewithtime80]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_qp_12.pdf

q 1: change in ox.no for Cr in option C is from 12 to 3 which has a difference of 9 ...then y is option B the right answer?

 

[donewithtime80]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_qp_12.pdf

q:3 how is a borohydride ion a tetrahydral?

how to go about the 4th question? i got my anwer close to the right answer...is it sth to just assume and write w/o a definite answer?

q:10 and 11 15 16 17 23 24 please...

q 19: why is the answer A and not D?

q:30 what's the difference between molecules in B and C except that they are reverse order of each other?

TIA

 

[forest822]

2) At constant temprature, Pv is proportional to n.
15) Answer is B?

Yes Answer is B

 

[awesomaholic101]

No, I first balanced Al and Na. Then I balanced O, then I saw there are 3 atoms of carbon present, so I knew that option A or C can come I saw option C, H molecules were not balancing so I tried with A.

ok thanx

 

[Metanoia]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_12.pdf

q 1: change in ox.no for Cr in option C is from 12 to 3 which has a difference of 9 ...then y is option B the right answer?

Oxidation state of Cr in Cr2O7 2- is +6 (not +12), we look at individual Cr, not the total of all Cr.

The "VI" in the name dichromate (VI) should already give us the idea that its oxidation state is +6.

 

[awesomaholic101]

can someone plz explain the 8th one

 

[awesomaholic101]

20th one ... how nucleophilic addition?

 

[Metanoia]

View attachment 57478
can someone plz explain the 8th one

Density of the gases is related to the Mr of the gases in the mixture and their % composition.

For example, for option A = 0.898 x 2 + 0.102 x 4 = 2.204
Repeat for the other options and choose the highest value among the 4 options.

 

[The Sarcastic Retard]

2) At constant temprature, Pv is proportional to n.
15) Answer is B?

No reaction between Mgcl2 and H2o

 

[awesomaholic101]

Density of the gases is related to the Mr of the gases in the mixture and their % composition.

For example, for option A = 0.898 x 2 + 0.102 x 4 = 2.204
Repeat for the other options and choose the highest value among the 4 options.

yes i had done that ... but i got a wrong answer ... the highest value is that of B, but answer is D

 

[The Sarcastic Retard]

yes i had done that ... but i got a wrong answer ... the highest value is that of B, but answer is D

Highest is for D. Check it.

 

[awesomaholic101]

Highest is for D. Check it.

ohk

 

[awesomaholic101]

Highest is for D. Check it.

yea sorry got it ... dunno wer i'd gone wrong :/

 

[The Sarcastic Retard]

yea sorry got it ... dunno wer i'd gone wrong :/

Sometimes this happens.

 

[awesomaholic101]

11th question plz

 

[The Sarcastic Retard]

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9701 - Chemistry/9701_w06_qp_1.pdf
Q11

 

[The Sarcastic Retard]

View attachment 57480
11th question plz

Use example of CH4
CH4 ----> C + 4H