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Chemistry: Post your doubts here!

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gary221 said:
Hey how do we solve this??​
untitled-png.8607
Ans is D​
Click to expand...
Assalamoalaikum wr wb!

first one...has no hydrogen bonding...cuz that exists in NH3 or HF or -OH so not A

dimeric..i dunno...let's check the other options :D

N to Al is a dative bond and Al to H is 3 covalent bonds...so total of 6 + 2 = 8 electrons therefor not C

yes...cuz there are no lone pairs, and 4 atoms attached...so tetrahedral structure...

P.S. Note that when a dative bond is formed...the lone pair that takes part will be considered as a bond pair..not really related to this...but I guess it's an imp point... :D
 
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umarashraf said:
its far too easy than the one you have answered...:p num of atoms = moles * Avogadro constant...
1g of Hydrogen has 1 mole... same as neon... 20/20.... moles= m/Mr
Click to expand...
:D
lol...
but the thing is i cant figure out how 1 g of hydrogen is 1 mole...
1 mole of hydrogen is 2 g, right? :s
 
umarashraf

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user said:
:D
lol...
but the thing is i cant figure out how 1 g of hydrogen is 1 mole...
1 mole of hydrogen is 2 g, right? :s
Click to expand...

you right mate... H2 has two hydrogen atoms... number of atoms will be 2*moles... for hydrogen 2*.5... for neon 1*1... for CO2 it will be 3*.5..(as carbon has 3 atoms , 2 of oxygen 1 carbon)
 
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umarashraf said:
you right mate... H2 has two hydrogen atoms... number of atoms will be 2*moles... for hydrogen 2*.5... for neon 1*1... for CO2 it will be 3*.5..(as carbon has 3 atoms , 2 of oxygen 1 carbon)
Click to expand...
oh ok,....get it now..
JazakAllah khairen... (y)

btw u sure ..right :D
 
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yar hmein school mein karwai he nahi gai... phy to asaan hai kaafi ... bs telecommunication mein masla hai thora... baqi chem ka to koi haal nahi...
 
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Ashique said:
For question 2, 2 double bonds in he compound were removed, thus 4 mole of hydrogen was required (since 2 hydrogens are added to the chain once you break a double bond). If you notice, CH2 was changed to CH3 thus one more mole os Hydrogen was required. So in total, 5 mole of hydrogen was required.

Question 3, first of all find the Mr of P2O5, which is (31*2)+(16*5)= 142.
Now find the amount of phosphorus present in this amount, which is (31*2)/142= 0.4366...
The question said, only 30% of it dissolves, so 0.4366*30= 13.09, which is almost equal to 13.1, hence answer is B.

Question 4-
Ethanol will not react with NaOH. Since a hydroxyl group is present in both of them, no nucleophilic substitution will happen, so it has to be ethanoic acid.

Question 5-
This question is hell tricky, and I've been trying this for half an hour now, and I don't see how to differentiate between A and D, both of 1 mol of A and D, will require 2 mol of HCN, and both will change the color of potassium dichromate.
I will try to brain storm this question with one of my friends, and she might come up with something. :p
Till then I'll be grateful if someone can reason out why it should be D, not A, please?
Here's the question:
attachment.php
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thank you soo much :D
 
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samwickz said:
10 At a total pressure of 1.0 atm, dinitrogen tetraoxide is 50% dissociated at a temperature of 60 oC, according to the following equation
N2O4 = > 2NO2

What is the value of the equilibrium constant, Kp, for this reaction at 60 oC?

A
1/3atm

B
2/3atm

C
4/3atm

D
2atm

helpppppppppppppppppppppppppppppppppppppppp the correct ans is C how 2 get it
Click to expand...
are you sure its C ? and your question is right ?
 
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