anyone there help me with chem mcq ?

[Pwincessajwa]

plz

 

[handsomeROB]

which mcq ......right it down !!!!

 

[Pwincessajwa]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w10_qp_12.pdf 2,12,14,11,7,4,6

 

[handsomeROB]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf 2,12,14,11,7,4,6

goog now u have done it ......and i totally dont no the answers ..hehehe...but wait someone will help u when helll read the post ...

 

[handsomeROB]

hey ur not in emergency right ??????reply

 

[Z.S.M]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf 2,12,14,11,7,4,6

Q2. B, because increase in temperature lowers and flattens the peak as more molecules attain higher energy.

 

[Z.S.M]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf 2,12,14,11,7,4,6

Q12. D (Periodic trends)

 

[Z.S.M]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf 2,12,14,11,7,4,6

Q4. B,
[1077+2(436)]-[3(410)+360+460] = -101

Energy of reactants minus energy of products.

 

[Z.S.M]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf 2,12,14,11,7,4,6

Q6. A

Energy at the peak (in a reaction) is always the activation energy that the reactants gain to initiate the reaction.

 

[Pwincessajwa]

goog now u have done it ......and i totally dont no the answers ..hehehe...but wait someone will help u when helll read the post ...

thank u so much

 

[Pwincessajwa]

Q6. A

Energy at the peak (in a reaction) is always the activation energy that the reactants gain to initiate the reaction.

q 14 ,19 plz ??
thankss

 

[Z.S.M]

q 14 ,19 plz ??
thankss

Could you link the ms?
So I maybe sure of my answers.

 

[Pwincessajwa]

Could you link the ms?
So I maybe sure of my answers.

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w10_ms_12.pdf here

 

[Z.S.M]

q 14 ,19 plz ??
thankss

Q19. C
Because chloride ion can NEVER be oxidised (replaced) by sulphate ion --> check electrochemical series..... so sulphuric acid will not act as an oxidizing agent. That omits options A and B altogether.
Iodide ion can be oxidised by sulphate. So C is the answer.

 

[Pwincessajwa]

Q19. C
Because chloride ion can NEVER be oxidised (replaced) by sulphate ion --> check electrochemical series..... so sulphuric acid will not act as an oxidizing agent. That omits options A and B altogether.
Iodide ion can be oxidised by sulphate. So C is the answer.

thank u so much its okey if i ask more queshtions ?

 

[Z.S.M]

q 14 ,19 plz ??
thankss

Q14. C

Topic: Thermal decomposition of group II nitrates

2Ca(NO3)2 --> 2CaO + 4NO2 + O2

NO2 and O2 will be liberated as gases. The residue is CaO.
Stoichiometric calculation:

Moles of calcium nitrate= 4.10/ (40+2x14+6x16) = 0.025
Mole ratio of calcium nitrate to calcium oxide = 1:1
Moles of CaO = 0.025
Mass of CaO = 0.025 x (40+16) = 1.40 g

 

[Z.S.M]

thank u so much its okey if i ask more queshtions ?

Sure.

 

[Pwincessajwa]

Q14. C

Topic: Thermal decomposition of group II nitrates

2Ca(NO3)2 --> 2CaO + 4NO2 + O2

NO2 and O2 will be liberated as gases. The residue is CaO.
Stoichiometric calculation:

Moles of calcium nitrate= 4.10/ (40+2x14+6x16) = 0.025
Mole ratio of calcium nitrate to calcium oxide = 1:1
Moles of CaO = 0.025
Mass of CaO = 0.025 x (40+16) = 1.40 g

i didnot understand

 

[Z.S.M]

i didnot understand

First you calculate the moles of the reactant from the mass by
moles = mass/ molar mass

then you put the molar ratio to calculate the moles of the product i.e residue --> CaO

then calculate the mass of product by rearranging the previously used formula

mass = moles x molar mass

 

[Pwincessajwa]

what about q 25 in the same ppr ?how will i khow ?