Chemistry: Post your doubts here!

[smzimran]

7 Which pair of elements have bonds of the same type between their atoms in the solid state?
A aluminium and phosphorus
B chlorine and argon
C magnesium and silicon
D sulphur and chlorine

why is the answer D and not A or B?

AoA,
Not A because Aluminium has metallic bonding while Phosphorus has a simple molecular struture with covalent bonds and Van der Waals forces
Not B because chlorine is diatomic (covalent bonding) while argon is a noble gas : monoatomic
Not C because Mg has metallic bonding while Silicon has covalent bonds
It is D because both have molecular structure with covalent bonds

 

[smartangel]

AoA,
Not A because Aluminium has metallic bonding while Phosphorus has a simple molecular struture with covalent bonds and Van der Waals forces
Not B because chlorine is diatomic (covalent bonding) while argon is a noble gas : monoatomic
Not C because Mg has metallic bonding while Silicon has covalent bonds
It is D because both have molecular structure with covalent bonds

thank you . plz explain these too.. http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_12.pdf
in Q6..shouldnt Y be higher as the peak increases when temp is reduced?
and plz explain Q 11, 19,23 as well!

 

[alphabravocharlie]

Yes, sorry. My bad! Wrote that in a hurry. There were too many questions and very little time. The answer still stays the same because the important point is the dissolution of HCl in water

Well yeah hcl is important

NO, I WAS RIGHT. YOU CONFUSED ME, ALPHA

You do have a short temper jk
Chill, Sicl4 dissolved in water can form: Sio2, Si[OH]4, H2SiO3, etc, And i got that from the past papers

 

[Nibz]

7 Which pair of elements have bonds of the same type between their atoms in the solid state?
A aluminium and phosphorus
B chlorine and argon
C magnesium and silicon
D sulphur and chlorine

why is the answer D and not A or B?

A wrong. Metallic - covalent
B wrong. Covalent - (mono atomic) or van der Waals
C wrong. metallic - covalent
D Right. Covalent - Covalent

 

[smartangel]

A wrong. In Al -> Metallic bonds. Phosphorus Covalent
B wrong. Chlorine -> Covalent. Argon -> monoatomic. No bonds.
D Right. Sulphur -> Covalent . Chlorin -> Covalent

thanks. just see if you can help me with the other questions i"ve posted above. thanks again

 

[Nibz]

Well yeah hcl is important

But SiO2 is equally important. I did not notice the 'white ppt.' part when I read the question after your correction.

You do have a short temper jk

Whatever.

 

[roadtrip9o9]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s08_qp_1.pdf 27,26,15,6,4 PLEASE ANSWER THESE .. i have written on this post like amillion times but it always gets ignored

 

[smartangel]

Q40..http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w09_qp_12.pdf

 

[roadtrip9o9]

In polymer there are many monomers so moles of the monomers will always decrease when they form a polymer ... So 1 (it wudnt remain the same) ... so when one is wrong answer will always be 'C' for these type of questions

 

[roadtrip9o9]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s08_qp_1.pdf 27,26,15,6,4

 

[Anoushay]

Hey,can anyone please explain the question number 13 in this paper??? i posted it before too. thanks.
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w10_qp_12.pdf

 

[hmlahori]

Can someone please explain these paper 1 questions?

​

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

http://www.xtremepapers.com/papers/...and AS Level/Chemistry (9701)/9701_w06_er.pdf​

Q6 How is hydrogen more ideal than nitrogen? ​

Q11 How should this question be solved?​

​

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_11.pdf​

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_er.pdf​

Q21 How does the compound have 5 double bonds. I counted 6(one in the side chain and 5 in the cyclohexene ring due to presense of just one hydrogen in it.)​

​

 

[geek101]

can someone please explain Q32 http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w07_qp_1.pdf

 

[roadtrip9o9]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s08_qp_1.pdf 27,26,15,6,4 PLEASE

 

[leadingguy]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w08_qp_4.pdf

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w08_ms_4.pdf

question 2 part b plz
I can see the ans. from m.s but can any one explain me how to drive the order of reactions here??? with respect to each??

 

[étudiante]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_qp_4.pdf

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_ms_4.pdf

question 2 part b plz
I can see the ans. from m.s but can any one explain me how to drive the order of reactions here??? with respect to each??

only substances in the slowest step r der in the rate eqn... thus if a substance is not present in da slow step, the order will become 0 automatically...
for the other substances, see the no of molecules of that substance involved in the slow step... the order will be the same number...
for the first one for instance..
step 1 doesnt have H= so its order is 0.. and there is only one molecule each of H2O2 and I- thus the order with respect to these two will be 1..


for step 3... its slightly different... we need to see how many molecules of the substance have been used up before as well... if u look back, we already used 1 molecule of I- in step 1 n 1 is again used in step 3 hence the ordr will be 2 with respect to I-

 

[geek101]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w07_qp_1.pdf Q9, someone! good luck to y'all!

 

[Jaf]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w07_qp_1.pdf Q9, someone! good luck to y'all!

Moles of metallic salt that reacted = (50/1000) * 0.1 = 0.005
Moles of sodium sulphite that reacted = (25/1000) * 0.1 = 0.0025
Therefore, the metallic salt and sodium sulphite react in the ratio (2:1).

Moles of electrons produced when 0.0025 moles of the sulphite ions react = 0.005 (mole ratio is 1:2 from equation).
Therefore, the mole ration of electrons:metallic salt is 1:1. Hence, each metal gains one electron. So the oxidation number changes from +3 to +2. Answer is B.

 

[leadingguy]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w07_qp_1.pdf Q9, someone! good luck to y'all!

mol of metalic salt n= cv

n= (0.10) . (0.050) = 0.0050
mol of sulphite n =cv

n= (0.10) . (0.025) = 0.0025

it has been given that 0.0050 mol of metal reacts with 0.0025 mol of sulphite mol ratio 2:1 metal/ sulphite

now when two electrons are released frm the sulphite's one mole.

only half of the released wil react with one mole of metal as shown above mol ratio 2:1

it has been given that the original oxidation no. of metal is +3 so when 1 elctron wil be added it wil be +2 !!!!


so it wil be the new oxidation no, i guess so B is to be the ans m i ryte??

 

[xxfarhaxx]

guys urgent ps... hlppp!!!
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s06_qp_1.pdf

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s06_ms_1.pdf
Q- 10, 17, 23, 26,33 ,40

god bless u alll!!!