Chemistry: Post your doubts here!

[*MK*skydiver :D]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_12.pdf

Q 11 you guys,It's been asked here for like 3 times and apparently it wasn't answered . can someone answer it for me ?
Can't think of an answer!


11 0.144 g of an aluminium compound X react with an excess of water, to produce a gas. This gas
burns completely in O2 to form H2O and 72 cm3
of CO2 only. The volume of CO2 was measured at
room temperature and pressure.

What could be the formula of X?
A Al 2C3 B Al 3C4 C Al 4C3 D Al 5C3

 

[Khadija_1234]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s04_qp_1.pdf
Please Help with Q1 and Q11

 

[Jessie N.]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_12.pdf

Q 11 you guys,It's been asked here for like 3 times and apparently it wasn't answered . can someone answer it for me ?
Can't think of an answer!


11 0.144 g of an aluminium compound X react with an excess of water, to produce a gas. This gas
burns completely in O2 to form H2O and 72 cm3
of CO2 only. The volume of CO2 was measured at
room temperature and pressure.

What could be the formula of X?
A Al 2C3 B Al 3C4 C Al 4C3 D Al 5C3

visit here：http://www.assignmentexpert.com/free-questions/question-on-chemistry-physical-chemistry-5313.html
or ：http://sgforums.com/forums/2297/topics/443584

both have some explanations，but I think we can get the answer by common sense: Al has ox. no of 3+ and C is 4- ?

 

[Jessie N.]

someone plz explain this

P1

Question :
Use of the Data Booklet is relevant to this question.
A washing powder contains sodium hydrogencarbonate, NaHCO3, as one of the ingredients. In a
titration, a solution containing 1.00 g of washing powder requires 7.15 cm3 of 0.100 mol dm–3
sulfuric acid for complete reaction. The sodium hydrogencarbonate is the only ingredient that
reacts with the acid.
What is the percentage by mass of sodium hydrogencarbonate in the washing powder?

Answer : 12

ˊ・ω・ˋ 〜

 

[Jessie N.]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s04_qp_1.pdf
Please Help with Q1 and Q11

Sorry for my poor English and handwriting ˊ_>ˋ hope you can understand.

 

[Jessie N.]

Help >~< Can someone explain it to me please???

 

[darknessinme]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_12.pdf

Q 11 you guys,It's been asked here for like 3 times and apparently it wasn't answered . can someone answer it for me ?
Can't think of an answer!


11 0.144 g of an aluminium compound X react with an excess of water, to produce a gas. This gas
burns completely in O2 to form H2O and 72 cm3
of CO2 only. The volume of CO2 was measured at
room temperature and pressure.

What could be the formula of X?
A Al 2C3 B Al 3C4 C Al 4C3 D Al 5C3

https://www.xtremepapers.com/community/threads/chemistry-mcq-thread.7567/page-82

I answered it there.

 

[darknessinme]

Help >~< Can someone explain it to me please???

With cold you get addition of two alcohol groups at double bond, so both the carbons involved in the double bond become chiral carbons, thus +2.
With hot, you get cleavage of the double bond, producing a ketone group and carboxylic acid group, however the don't turn into chiral carbons. Carbon attached to alcohol group on far left is chiral, but the OH gets oxidised to ketone, so carbon is no longer chiral, thus -1.
Answer: D

 

[immie.rose]

I urgently need the answers to the End-of-chapter questions of Cambridge Chemistry Coursebook. Can somebody PLEASE pass em on? Pretty Please?

 

[Browny]

If possible please answer the following and if possible leave out all the periodicity questions, questions on groups and on nitrogen and sulphur because I haven't gone through them and don't know whether the questions are from those units. Please do answer the other questions including the one on contact process and haber process.



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

Q5, Q11, Q17, Q19, Q31

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w07_qp_1.pdf

Q5, Q6, Q9, Q21, Q32, Q35, Q36, Q37

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s06_qp_2.pdf

Q1) a) iii)

Q2) e) ii)

Q4) c)
e)

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w06_qp_2.pdf

Q5) d)
f)

 

[Kinki Tiffany 12]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s10_qp_11.pdf

can anyone help me with question 4, 10 and 11 ?

 

[Khadija_1234]

Sorry for my poor English and handwriting ˊ_>ˋ hope you can understand.

Thank you so much

 

[Jessie N.]

With cold you get addition of two alcohol groups at double bond, so both the carbons involved in the double bond become chiral carbons, thus +2.
With hot, you get cleavage of the double bond, producing a ketone group and carboxylic acid group, however the don't turn into chiral carbons. Carbon attached to alcohol group on far left is chiral, but the OH gets oxidised to ketone, so carbon is no longer chiral, thus -1.
Answer: D

Thankyouuuuu

 

[Jinosupreme]

Answer is B. Why answer can't be D? It is also correct right?

 

[Jinosupreme]

How to do? Answer is D

 

[Jinosupreme]

An element X and compound YZ react separately with acid as shown.
X(s) + 2H+(aq) → X2+(aq) + H2(g)
YZ(s) + 2H+(aq) → Y2+(aq) + H2Z(g)
When 1.0 g of either X or YZ is reacted with an excess of acid, the total volume of gas formed is the same.
Which statements are correct?
1. Ar(X) = Mr(YZ)
2. X and Y are metals.
3. X and Y must both be in the same Group of the Periodic Table.

Answer is 1 & 2 why?

 

[*MK*skydiver :D]

https://www.xtremepapers.com/community/threads/chemistry-mcq-thread.7567/page-82

I answered it there.

Thank you ! I really appreciate it

 

[*MK*skydiver :D]

visit here：http://www.assignmentexpert.com/free-questions/question-on-chemistry-physical-chemistry-5313.html
or ：http://sgforums.com/forums/2297/topics/443584

both have some explanations，but I think we can get the answer by common sense: Al has ox. no of 3+ and C is 4- ?

hahahaha, common sense doesn't always work with Chemistry there are alwaaaysss exceptions !

*complications , complications*

Thank you for the answers; helpful

 

[Jessie N.]

hahahaha, common sense doesn't always work with Chemistry there are alwaaaysss exceptions !

*complications , complications*

Thank you for the answers; helpful

LOL so true

 

[Jessie N.]

Answer is B. Why answer can't be D? It is also correct right?

For D，the first and the second one is the same. Try to draw out the displayed formula then you will notice it.