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Chemistry: Post your doubts here!
- Thread starter XPFMember
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Since when is a base an acceptor of OH^- ions?
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I said OH- donor. Hence, a H+ acceptor.
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i have some questions in chemistry P1 May/June 2007
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s07_qp_1.pdf
Q9
Q18
Q27
Q40
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s07_qp_1.pdf
Q9
Q18
Q27
Q40
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Never heard of that kind of logic..
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lol... I was just trying to make sense of the question I dunno the answer to. Maybe my head's starting to rust. Signing off now . Adios
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Bye, and a penny for you thoughts... is that ion even a Lewis base?
Q9) theres kind of a shorcut explanaion to this, since the products of reaction two are 1/2 moles, so its going to be anything with a power of 1/2 which is actually square root, the only option with an underroot 2 is A.
Q18) the solid nitrate is NH4NO3 > N2H4O3
Q27) propanal and propan-2-ol both have the tendency to be oxidized. propanal to propanoic acid and propan-2-ol to propanone. When they get oxidized both change the colour of KMnO4 from orange to green.
Q40) inorder to break an ester bond there must be either a dilute acid or alkali. the only of these is 1 (acid), thus being the only answer. heres a little info on ester hydrolysis...
http://www.chemguide.co.uk/organicprops/esters/hydrolysis.html
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Yes thats what i thought it would be but i still wasnt sure. well thanks!
XPFMember
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Assalamoalaikum wr wb!
need help in these mcqs, please:
need help in these mcqs, please:
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Walikum Salaam!
28 - A is a test for aldehyde.
C is test for both aldehyde and ketone.
D is used for the reduction of carbonyl compounds.
B is the correct answer as it is test for alkenic double bond. Cyclohexene having double bond will discharge the colour of Br2 while cyclohexanol won't...
35- Not sure.
36-
X can be Carbon, Nitrogen and Sulpher.
Y can be CO, NO, SO2.
Z can be CO2, NO2. (No SO3, Oxidation of SO2 requires catalyst so its not on the spot reaction.)
1- It does increase for NO and CO.
2- CO and SO2 does have lone pairs.
3- CO2 and NO2 have two oxygen atoms.
So only 1 is correct.
10- Acid is a proton donor, Base is aproton acceptor. In the second reaction HSO3- accepts the proton making it a base. Further explained here : Chemistry: Post your doubts here!
35.
1 - Ammonium Salt with strong base gives ammonia.
2- Neutralization Reaction. So that is correct too.
3- Limewater absorbs CO2 making limestone.
A is the answer.
36 - X can be Carbon, Nitrogen and Sulpher.
Y can be CO, NO, SO2.
Z can be CO2, NO2. (Oxidation of SO2 requires catalyst Vanadium Oxide so it is not on the spot reaction)
1- X forms a basic hydride is correct as NH3 is basic.
2- Y is a diatomic molecule is correct as you can see CO and NO are diatomic.
3- Z is a polar molecule. NO2 is polar.
So all are correct making the answer A.
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Cud sum1 tell me hw v calculate the no. of moles required?? Ans is C, btw
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first try understanding in terms of ethene...
ethene has 1 double bond ryt? if u saturate it, u get ethane... draw out these 2 n see how many H is extra (u will see its 2)
now apply dis 2 da question... how many bonds do we need 2 saturate? 5 in total ryt? count it out, 1 bond in 1 chain n 2 bonds in the oder 2... dat makes 5 moles...
(as 1 mole of H2 has 2 moles of H atoms in it...)
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oh bt hw did u know 5 bonds hv been saturated??
thnx, nywy...
P.S. I m kinda bad at organic chem...
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see the question... in the residue molecule, dere is 1 double bond left in da molecule n 2 in da oder 1.. n dere r 2 moles of the second molecule..oh bt hw did u know 5 bonds hv been saturated??
thnx, nywy...
P.S. I m kinda bad at organic chem...
so dats 1 + 2(2) = 5
ur welcum...
dats wat u think.... its jst practice
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Answer is B. Explain?
XPFMember
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Assalamoalaikum wr wb!
yup..
enthalpy change of formation is the formation of 1 mole of product, with the reactants and products in the standard state...!!
iodine is solid under standard conditions...so total enthalpy change of formation of 2 moles of ICl3 is 38 + -214 = -176
standard is for one mole so -176/2 = -88
It says that one side chain is converted to a compound with 2 double bonds instead of 3, which means one bond was hydrogenated, so one mole of H2 was used. Then it says that 2 chains were converted to compounds with only one double bond each, which means that 2 bonds were hydrogenated per chain, so 2 moles of H2 used per chain. Now if you add em up its 1 mole for the first chain, 2 moles for the second, and 2 moles for the third. So 5 moles of H2 were used.
http://www.freeexampapers.com/downl... Jun/9701_s02_qp_1.pdf&t1=30q1nf6&t2=349iacp6
can anyone please explain Q6! thank youu
can anyone please explain Q6! thank youu