Chemistry: Post your doubts here!

[smzimran]

How many structural and cis-trans isomers are there for dichloropropene, C3H4Cl2?
A 3 B 5 C 6 D 7
is there any other way other than drawing all of them?

Unfortunately, there isn't
I have solved this before as well!

 

[smzimran]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w03_qp_1.pdf
Q27..why is the answer sulfuric acid..can someone plz tell me the rxn these compounds undergo with H2SO4?

Elimination reaction
The elimination of water to form double bond (alkene)
Check some text book for detail

 

[smzimran]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w05_qp_1.pdf Q20..im sorry the answer is B. my question is that whats the other isomer besides cis trans?

The other (third) isomer is:
(Cl2)C = C(H2)

 

[smzimran]

More doubts x_x . The correct answers are circled.View attachment 8831

AoA,
First of all, we know CS2 is the limiting reactant
So 10 cm3 CS2 needs 30 cm3 O2 (See molar ratio)
That means 50 - 30 = 20 cm3 O2 is left after the reaction
Further,
10 cm3 CO2 and 20 cm3 SO2 are produced (See molar ratio)
So total volume of gases left after burning = 20 cm3 O2 + 10 cm3 CO2 + 20 cm3 SO2 = 50 cm3

The answer must be either C or D

Adding NaOH will neutralise (or remove) acidic gases
It will remove 10 cm3 CO2 and 20 cm3 SO2 = 30 cm3 acidic gases
Gas left after NaOH is added = 50 - 30 = 20 cm3

So, C is correct!

 

[Anoushay]

u r wecome, it is correctly balanced equation and they ask u 4 which you put in front of (as far as i remember the question) I2 and H2O, u understand now?

umm...no. can you please elaborate.?

 

[saudha]

Which of these samples of gas contains the same number of atoms as 1g of hydrogen
(Mr
: H2, 2)?
A 22g of carbon dioxide (Mr
: CO2, 44)
B 8 g of methane (Mr
: CH4, 16)
C 20 g of neon (Mr
: Ne, 20)
D 8g of ozone (Mr
: O3, 48)

 

[saudha]

hieeee...

if there are diagrams in the Q... then just post Q no an d the ppr ur solving.. ok

 

[étudiante]

Which of these samples of gas contains the same number of atoms as 1g of hydrogen
(Mr
: H2, 2)?
A 22g of carbon dioxide (Mr
: CO2, 44)
B 8 g of methane (Mr
: CH4, 16)
C 20 g of neon (Mr
: Ne, 20)
D 8g of ozone (Mr
: O3, 48)

C since they are talking abt atoms....
1 g of H2 gas will have 6.02 x 10^22 ATOMS as it is diatomic... Neon will also have the same no of atoms in 20 g as it is monatomic

 

[saudha]

C since they are talking abt atoms....
1 g of H2 gas will have 6.02 x 10^22 ATOMS as it is diatomic... Neon will also have the same no of atoms in 20 g as it is monatomic

thxx a lot

 

[étudiante]

thxx a lot

ur welcum
remmeber me in ur prayers please

 

[saudha]

will do inshallah.... do the same 4 me

 

[étudiante]

will do inshallah.... do the same 4 me

sure Inshallah

 

[angelgirl:)]

The Haber process for the manufacture of ammonia is represented by the following equation
N2
(g) + 3H
(g) 2NH(g) *H = –92kJmol
　




Which statement is correct about this reaction when the temperature is increased?
A Both forward and backward rates increase.
B The backward rate only increases.
C The forward rate only increases.
D There is no effect on the backward or forward rate.

y the answer is A instead of B ?

 

[étudiante]

The Haber process for the manufacture of ammonia is represented by the following equation
N2
(g) + 3H
(g) 2NH(g) *H = –92kJmol
　




Which statement is correct about this reaction when the temperature is increased?
A Both forward and backward rates increase.
B The backward rate only increases.
C The forward rate only increases.
D There is no effect on the backward or forward rate.

y the answer is A instead of B ?

because they are talking about RATE. the rate ALWAYS increases with temperature and in both directions

 

[angelgirl:)]

saudha?

 

[angelgirl:)]

because they are talking about RATE. the rate ALWAYS increases with temperature and in both directions

oh... thanks..

 

[étudiante]

oh... thanks..

ur welcome

 

[Amaryllis]

hi
i have some doubts
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s07_qp_1.pdf
q no. 3 why A it should be B
q 12
q26 can anybody explain it please
q32 why its C graphite contains only vanderwaals force

 

[saudha]

saudha?

yah?

 

[étudiante]

hi
i have some doubts
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s07_qp_1.pdf
q no. 3 why A it should be B
q 12
q26 can anybody explain it please
q32 why its C graphite contains only vanderwaals force

it cant be B because atoms CAN be split into subatomic particles.. (remmeber frm physics )
C
Q26..
it has to be a tertiary alcohol as it doesn't react wid MnO4- ..... chiral carbon so we need three differnt groups... (the general formula shows dat there are no C+C either)
draw it out n u'll see the best way will be to have a central C wid one -OH grp, one methyl, one ethyl and one propyl grp attatched... thus 7 atoms required