# Chemistry: Post your doubts here!

#### Bba321

Hi
Can anyone tell me if we write 4s and then 3d in group 4 elements like Ge,Sn and Pb or do we write 3d or the other way?

Thanks

#### Snowysangel

Could someone please explain the reaction between iodine and thiosulfate ions to me?

Q29

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#### Paris Palmer

HCl is a polar molecules. H has a partial positive charge while Cl has a partial negative charge since chlorine is highly electronegative compared to hydrogen. The force between HCl molecules is permanent dipole attraction. Not induced dipole forces.
Why is the Ionic Radius of transition elements invariant?

hi guys,
i want a lvl chem past papers of 1996 if any1 have it plz upload it soon.
according to my knowledge kgs library contains it.

#### Paris Palmer

hi guys,
i want a lvl chem past papers of 1996 if any1 have it plz upload it soon.
according to my knowledge kgs library contains it.
Can someone please send me a link to download Chem A Levels pastpapers of June 2014?

How is it C??

#### princess Anu

The ratio of volume of gases is the ratio of their moles
So 1:3:1:1:1 is the ratio shown by the equation but the ratio given is 1:6
therefore 30cm of O2 will be used leaving the excess (30cm)
and we get 10 cm of CO2, h20 nd SO2 makes a total of 6o. But since the mixture is cooled, h20 will convert into water and so the remaining volume will be 50.

#### Awesome12

The ratio of volume of gases is the ratio of their moles
So 1:3:1:1:1 is the ratio shown by the equation but the ratio given is 1:6
therefore 30cm of O2 will be used leaving the excess (30cm)
and we get 10 cm of CO2, h20 nd SO2 makes a total of 6o. But since the mixture is cooled, h20 will convert into water and so the remaining volume will be 50.
Thanks.

Why is it B?

#### princess Anu

The dipoles in A C D cancel out but not in B.
Remember, Trigonal planar shaped molecules can cancel dipoles if all the bonds made are polar, like in C.

Last edited:

#### Awesome12

The dipoles in A B D cancel out but not in C.
Remember, Trigonal planar shaped molecules can cancel dipoles if all the bonds made are polar, like in C.
But the answer is B. And both B and C are trigonal planar shaped molecules.

#### princess Anu

But the answer is B. And both B and C are trigonal planar shaped molecules.
Like I said, IF ALL THE BONDS ARE POLAR. Therefore C has no dipoles while B has.
Sorry, I mistyped. It's 'The dipoles in A C D cancel out but not in B'.

#### slisjunknown

I do not understand the periodic trends in period 3 for electrical conductivity, boiling points, ionic radii and atomic radii. many sources show different graph representation. It would be highly appreciated if anyone can explain the graphs for the properties. Is there any specific way to place values in the graphs? Cuz my teacher says you have to guess the values...

#### savera

I do not understand the periodic trends in period 3 for electrical conductivity, boiling points, ionic radii and atomic radii. many sources show different graph representation. It would be highly appreciated if anyone can explain the graphs for the properties. Is there any specific way to place values in the graphs? Cuz my teacher says you have to guess the values...
I hope this helps. If not don't hesitate to ask questions