Chemistry MCQ thread...

[histephenson007]

Q.

Use of the data booklet is relevant to this question.

What volume of oxygen, measured under room conditions, can be obtained from the thermal decomposition of 8.2g of Calcium nitrate (Mr=164)?
A. 150 cm^3
B. 300 cm3
C. 600 cm3
D. 1200 cm3

answer is D

That was my answer as well, but the mark scheme says its C... - -

 

[hassam]

 

[xHazeMx]

Q.

Use of the data booklet is relevant to this question.

What volume of oxygen, measured under room conditions, can be obtained from the thermal decomposition of 8.2g of Calcium nitrate (Mr=164)?
A. 150 cm^3
B. 300 cm3
C. 600 cm3
D. 1200 cm3

answer is D

That was my answer as well, but the mark scheme says its C... - -

i think u didnt divide the number of moles by 2
the equation is 2Ca(NO3)2 --------> 2CaO + 4NO2 + O2
number of moles of oxygen is half of that of calcium nitrate
u should get the answer now

 

[hassam]

When 0.10 g of magnesium was added to 100 cm3 of 0.10 mol dm-3 dilute sulfuric
acid in a calorimeter (with negligible heat capacity), a maximum temperature rise
of 5.8 oC was recorded. What is the enthalpy change of this reaction?
A – 589 kJ mol-1 B – 242 kJ mol-1
C – 172 kJ mol-1 D – 28.4 kJ mol-1

 

[xHazeMx]

D

 

[Zishi]

D

 

[hassam]

yes

 

[histephenson007]

Q.

Use of the data booklet is relevant to this question.

What volume of oxygen, measured under room conditions, can be obtained from the thermal decomposition of 8.2g of Calcium nitrate (Mr=164)?
A. 150 cm^3
B. 300 cm3
C. 600 cm3
D. 1200 cm3

no its C

Could you plz give me the equation of the nitrate decomposition for this reaction?

 

[Zishi]

ZISHI...1 IS ALSO CORRECT AND ITS a... JUst stick with the use of oxidation numbers

No, I'll stick with C 'til I get it confirmed. Is A given in the mark scheme OR a book?

 

[xHazeMx]

When 0.10 g of magnesium was added to 100 cm3 of 0.10 mol dm-3 dilute sulfuric
acid in a calorimeter (with negligible heat capacity), a maximum temperature rise
of 5.8 oC was recorded. What is the enthalpy change of this reaction?
A – 589 kJ mol-1 B – 242 kJ mol-1
C – 172 kJ mol-1 D – 28.4 kJ mol-1

should we use the Q=mcDT in this question ????

 

[abdullah181994]

Hi pros here.. please help me

3 The foul smell that skunks spray is due to a number of thiols, one of which is methanethiol,
CH3SH, which burns as follows.
CH3SH + 3O2 → CO2 + SO2 + 2H2O
A sample of 10 cm3 of methanethiol was exploded with 60 cm3 of oxygen.
What would be the final volume of the resultant mixture of gases when cooled to room
temperature?
A 20 cm3 B 30 cm3 C 50 cm3 D 70 cm3

19 Ammonium sulphate in nitrogenous fertilisers in the soil can be slowly oxidised by air producing
sulphuric acid, nitric acid and water.
How many moles of oxygen are needed to oxidise completely one mole of ammonium sulphate?
A 1 B 2 C 3 D 4

and please help me with oct nov 04 no 10 11 12 and 21.. i cant paste it here because there are pictures and tables..

3:C because 30cm3 of O2 does not reacted +10cm3 of CO2+10cm3 of SO2
19:A not sure

 

[Hateexams93]

ZISHI...1 IS ALSO CORRECT AND ITS a... JUst stick with the use of oxidation numbers

No, I'll stick with C 'til I get it confirmed. Is A given in the mark scheme OR a book?

what is the oxidation number of elements in C2H5* (radical ) ?????

 

[xHazeMx]

Q.

Use of the data booklet is relevant to this question.

What volume of oxygen, measured under room conditions, can be obtained from the thermal decomposition of 8.2g of Calcium nitrate (Mr=164)?
A. 150 cm^3
B. 300 cm3
C. 600 cm3
D. 1200 cm3

no its C

Could you plz give me the equation of the nitrate decomposition for this reaction?

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

 

[Zishi]

ZISHI...1 IS ALSO CORRECT AND ITS a... JUst stick with the use of oxidation numbers

No, I'll stick with C 'til I get it confirmed. Is A given in the mark scheme OR a book?

what is the oxidation number of elements in C2H5* (radical ) ?????

One carbon has 3, and another one has 4. and of course, all H atoms have 1.

 

[kirashinagami]

Hi pros here.. please help me

3 The foul smell that skunks spray is due to a number of thiols, one of which is methanethiol,
CH3SH, which burns as follows.
CH3SH + 3O2 → CO2 + SO2 + 2H2O
A sample of 10 cm3 of methanethiol was exploded with 60 cm3 of oxygen.
What would be the final volume of the resultant mixture of gases when cooled to room
temperature?
A 20 cm3 B 30 cm3 C 50 cm3 D 70 cm3

19 Ammonium sulphate in nitrogenous fertilisers in the soil can be slowly oxidised by air producing
sulphuric acid, nitric acid and water.
How many moles of oxygen are needed to oxidise completely one mole of ammonium sulphate?
A 1 B 2 C 3 D 4

and please help me with oct nov 04 no 10 11 12 and 21.. i cant paste it here because there are pictures and tables..

3:C because 30cm3 of O2 does not reacted +10cm3 of CO2+10cm3 of SO2
19:A not sure

3 is C, how can you find 30 cm3 of 02?
19 is D, can you explain why it is D??
thank you so much btw

can others help me with oct nov 04 no 10,11,12 and 21??

 

[xHazeMx]

One carbon has 3, and another one has 4. and of course, all H atoms have 1.

check 1 again carbon is reduced and oxidised check the oxidation numbers of C2 and C3 in the products

 

[Zishi]

When 0.10 g of magnesium was added to 100 cm3 of 0.10 mol dm-3 dilute sulfuric
acid in a calorimeter (with negligible heat capacity), a maximum temperature rise
of 5.8 oC was recorded. What is the enthalpy change of this reaction?
A – 589 kJ mol-1 B – 242 kJ mol-1
C – 172 kJ mol-1 D – 28.4 kJ mol-1

There's a misprint in it I guess, we need a heat capacity or specific heat capacity...

 

[Zishi]

One carbon has 3, and another one has 4. and of course, all H atoms have 1.

check 1 again carbon is reduced and oxidised check the oxidation numbers of C2 and C3 in the products

I guess I concentrated on one carbon atom only. You were correct.

 

[xHazeMx]

When 0.10 g of magnesium was added to 100 cm3 of 0.10 mol dm-3 dilute sulfuric
acid in a calorimeter (with negligible heat capacity), a maximum temperature rise
of 5.8 oC was recorded. What is the enthalpy change of this reaction?
A – 589 kJ mol-1 B – 242 kJ mol-1
C – 172 kJ mol-1 D – 28.4 kJ mol-1

There's a misprint in it I guess, we need a heat capacity or specific heat capacity...

thats what i m thinking too but does the part (with negligible heat capacity) mean anything??

 

[xHazeMx]

One carbon has 3, and another one has 4. and of course, all H atoms have 1.

check 1 again carbon is reduced and oxidised check the oxidation numbers of C2 and C3 in the products

I guess I concentrated on one carbon atom only. You were correct.

no problem u r still the master