Chemistry: Post your doubts here!

[Hisham Khan]

I was really good in chem in olevels.Even in A levels now... but I dont know why I just don;'t have a liking for the chem mcs.
bio mcs were intresting needed some thinking.chem is just you know or you don't know thingy

 

[Ebrahim12]

View attachment 64025
help?

Write the equations to get the amount of O2 needed for one mole of each element:

Mg + 1/2 O2 → MgO
Al + 3/4 O2 → 1/2 Al2O3
S8 + 12 O2 → 8SO3

So its 0.5, 0.75, 12.

 

[Daniyal(sda)]

View attachment 64023
ANS B can anyone explain why it is slower than iodoethane

Bond energy of C-Br bond is higher than C-I bond, so the C-Br bond takes more energy (more time) to break
Thus the reaction is slower than the one in iodomethane

 

[Kanekii]

View attachment 64025
help?

Mg + O2 = MgO
2Al + 1.5O2 = Al2O3
S + 1.5O2 = SO3
Rest is self explanatory.

 

[Hisham Khan]

Isint F second element

 

[Daniyal(sda)]

why b?
View attachment 64013

A and D are non polar
In B the two H atoms have way less electronegativity than the two Cl atoms in C so the difference in electronegativity is greater in option B than C so molecule in B is more polar

 

[Kanekii]

Help and Explain

 

[Daniyal(sda)]

Isint F second elementView attachment 64027

Highest ionisation energies are always of the noble gases so the one before them are halides, only halide in the options is F

 

[Hisham Khan]

Highest ionisation energies are always of the noble gases so the one before them are halides, only halide in the options is F

thanks

 

[Kanekii]

Help And Explain.

 

[Kanekii]

Help and Explain

 

[MShaheerUddin]

Help Needed urgent

 

[Daniyal(sda)]

Help and ExplainView attachment 64028View attachment 64029

In 38:
1 the sum of the Mr in the monomer is 62.5 so the Mr of the polymer will be the multiples of 62.5
2just make a displayed formula you will observe that there is only one chiral per monomer in the polymer
3 there will be 7 sigma bonds not 5 as the carbon atoms in each monomer will make a sigma bond with the carbon atom of the next monomer

In 26 only in option D will there be a single C=C, between the carbon of OH group and carbon of the ring attached to it

 

[Kanekii]

Help Needed urgent

B?

 

[A*****]

But it says pressure constant?

It is same

 

[Daniyal(sda)]

Help Needed urgent

Is the answer D
If it is then it is because one Cl atom can substitute a H from any C atom only substituting the H atom from the three methyl group will make the same structure

 

[A*****]

Mg + O2 = MgO
2Al + 1.5O2 = Al2O3
S + 1.5O2 = SO3
Rest is self explanatory.

Do we take S or S8??

 

[A*****]

Help Needed urgent

It is B bqz attaching on the methyl groups will result in the same molecule beimg made so attaching on 1 methyl group and the other 2 carbons gives B

 

[Kanekii]

Do we take S or S8??

won't the S8 bonds be broken since its heated in excess oxygen?

 

[Hisham Khan]

It is B bqz attaching on the methyl groups will result in the same molecule beimg made so attaching on 1 methyl group and the other 2 carbons gives B

We take S8