Chemistry MCQ thread...

[Zishi]

A chloroalkane W with molecular formula of C5H11Cl exhibits optical activity. On warming
W with alcoholic NaOH, two alkenes X and Y are formed, X being the major product.
One of the products of the reaction between X and hot acidified potassium
manganate(VII) gives a yellow precipitate with alkaline aqueous iodine. Which of the
following could be W?
A CH3CHClCH2CH2CH3 C CH3CH(CH3)CHClCH3
B CH3CH2CHClCH2CH3 D CH3CCl(CH3)CH2CH3

It's in A2 because of alkaline Iodine thing.

 

[xHazeMx]

A chloroalkane W with molecular formula of C5H11Cl exhibits optical activity. On warming
W with alcoholic NaOH, two alkenes X and Y are formed, X being the major product.
One of the products of the reaction between X and hot acidified potassium
manganate(VII) gives a yellow precipitate with alkaline aqueous iodine. Which of the
following could be W?
A CH3CHClCH2CH2CH3 C CH3CH(CH3)CHClCH3
B CH3CH2CHClCH2CH3 D CH3CCl(CH3)CH2CH3

A

 

[xHazeMx]

A chloroalkane W with molecular formula of C5H11Cl exhibits optical activity. On warming
W with alcoholic NaOH, two alkenes X and Y are formed, X being the major product.
One of the products of the reaction between X and hot acidified potassium
manganate(VII) gives a yellow precipitate with alkaline aqueous iodine. Which of the
following could be W?
A CH3CHClCH2CH2CH3 C CH3CH(CH3)CHClCH3
B CH3CH2CHClCH2CH3 D CH3CCl(CH3)CH2CH3

It's in A2 because of alkaline Iodine thing.

u can just solve it by checking the chiral centres its A

 

[Zishi]

B.

 

[xHazeMx]

A

 

[diwash]

Why is hydrogen iodide a stronger acid than hydrogen chloride?
A A molecule of hydrogen chloride is more polar than a molecule of hydrogen
iodide.
B The enthalpy change of formation of hydrogen iodide is greater than that of
hydrogen chloride.
C The covalent bond in the hydrogen iodide molecule is weaker than that in the
hydrogen chloride molecule.
D The dissociation of hydrogen chloride molecules is suppressed by the stronger
permanent dipole–permanent dipole interactions.

C ?

Because of the weak covalent bonding between the H and I atom...HI can get easily dissociate..and almost completely( as a strong acid is an acid which gets completely dissociated)....where as HF bond is strong so can not dissociate ...therefore HI is stronger acid than HF.

 

[xHazeMx]

B.

Aldehyde group reacts with hydrogen ??? if yes then the answer is B by eliminating though i dont understand how is it condensation :%)

 

[Zishi]

Hassam? B is the correct answer to that cis-retinal question.

 

[Mssamgirl15]

QUESTION 31 OCTOBER/NOVEMBER 2009

A monomer undergoes addition polymerisation. A 1 mol sample of the monomer is completely
polymerised.
How many moles of polymer might, theoretically, be formed?
1 1
2 10^–6
3 1 (divided by) 6.02 into 10^23

 

[Zishi]

B.

Aldehyde group reacts with hydrogen ??? if yes then the answer is B by eliminating though i dont understand how is it condensation :%)

Nope. H2 can't reduce aldehydes. And condensation reaction is one in which a water molecule is lost.

 

[xHazeMx]

Nope. H2 can't reduce aldehydes. And condensation reaction is one in which a water molecule is lost.

why is it not A? 5 double bonds ( C=C ) so 5 moles of hydrogen isn't it ?

 

[Zishi]

QUESTION 31 OCTOBER/NOVEMBER 2009

A monomer undergoes addition polymerisation. A 1 mol sample of the monomer is completely
polymerised.
How many moles of polymer might, theoretically, be formed?
1 1
2 10^–6
3 1 (divided by) 6.02 into 10^23

2 and 3. I'd leave the explanation to xHazeMx...he's good at it.

Nope. H2 can't reduce aldehydes. And condensation reaction is one in which a water molecule is lost.

why is it not A? 5 double bonds ( C=C ) so 5 moles of hydrogen isn't it ?

There are six double bonds.

 

[xHazeMx]

QUESTION 31 OCTOBER/NOVEMBER 2009

A monomer undergoes addition polymerisation. A 1 mol sample of the monomer is completely
polymerised.
How many moles of polymer might, theoretically, be formed?
1 1
2 10^–6
3 1 (divided by) 6.02 into 10^23

is it C ?

 

[Zishi]

QUESTION 31 OCTOBER/NOVEMBER 2009

A monomer undergoes addition polymerisation. A 1 mol sample of the monomer is completely
polymerised.
How many moles of polymer might, theoretically, be formed?
1 1
2 10^–6
3 1 (divided by) 6.02 into 10^23

is it C ?

Yep, it's C. Just explain it to him.

 

[xHazeMx]

There are six double bonds.

no there is 5 C=C and 1 C=O check it again. C=O cant be hydrogenated. i guess the answer is A

 

[abdullah181994]

please answer this ,correct answer is D .please also explian.

 

[xHazeMx]

QUESTION 31 OCTOBER/NOVEMBER 2009

A monomer undergoes addition polymerisation. A 1 mol sample of the monomer is completely
polymerised.
How many moles of polymer might, theoretically, be formed?
1 1
2 10^–6
3 1 (divided by) 6.02 into 10^23

is it C ?

Yep, it's C. Just explain it to him.

i dont think my explanation can justify that fully. i will leave it to u zishi .. just don't want to share doubtful information

 

[xHazeMx]

please answer this ,correct answer is D .please also explian.

tell me the exam's year and question number. i cant open .docx files for some reasons

 

[hassam]

well i guess h2 cn reduce.... c=0 saw it somewher in theory ms
here it is NaBH4 or LiAlH4 or H2/Ni (1) /....this is taken from m/j 08 p2 ms...zishi !!!

 

[diwash]

oo..then what's the answer hassam....