Chemistry MCQ thread...

[Octahedral]

Can someone please explain Q 21 s10_qp_11?

 

[xHazeMx]

bring some more questions hassam !!

 

[abdullah181994]

can a ester react with carboxlic acid

no

40 Fats and grease that build up on pans used in cooking are esters. Pans which are dirty from fats
or grease may be cleaned by heating them with a reagent that will react with the ester group.
What may be used to clean such pans by this reaction?
1 vinegar - aqueous ethanoic acid, CH3CO2H
2 alcohol - ethanol, C2H5OH
3 baking powder - sodium hydrogencarbonate, NaHCO3
look at this its correct answer is 1(D) it means C.ACID reacts with ester

 

[hassam]

The Voyager 2 probe has shown that the surface of Triton, a moon of the planet
Neptune, contains solid methane which flows rapidly.
Which statement best explains the mobility of solid methane?
A Methane molecules contain strong C-H bonds.
B Solid methane has a metallic structure.
C The intermolecular forces between methane molecules are weak.
D Triton has a low atmospheric pressure.

 

[hassam]

The standard enthalpy changes of formation of carbon dioxide and water are
−394 kJ mol-1 and −286 kJ mol-1 respectively.
If the standard enthalpy change of combustion of propyn, C3H4, is −1938 kJ mol-1,
what is its standard enthalpy change of formation?
A +184 kJ mol-1 C +284 kJ mol-1
B −184 kJ mol-1 D −284 kJ mol-1

 

[Zishi]

The Voyager 2 probe has shown that the surface of Triton, a moon of the planet
Neptune, contains solid methane which flows rapidly.
Which statement best explains the mobility of solid methane?
A Methane molecules contain strong C-H bonds.
B Solid methane has a metallic structure.
C The intermolecular forces between methane molecules are weak.
D Triton has a low atmospheric pressure.

C

 

[abdullah181994]

can a ester react with carboxlic acid

no

But it can hydrolyse an ester up to a "VERY" low extent. There was a MCQ about it.

THANKS @ zishi

 

[Zishi]

The standard enthalpy changes of formation of carbon dioxide and water are
−394 kJ mol-1 and −286 kJ mol-1 respectively.
If the standard enthalpy change of combustion of propyn, C3H4, is −1938 kJ mol-1,
what is its standard enthalpy change of formation?
A +184 kJ mol-1 C +284 kJ mol-1
B −184 kJ mol-1 D −284 kJ mol-1

A

 

[abdullah181994]

The Voyager 2 probe has shown that the surface of Triton, a moon of the planet
Neptune, contains solid methane which flows rapidly.
Which statement best explains the mobility of solid methane?
A Methane molecules contain strong C-H bonds.
B Solid methane has a metallic structure.
C The intermolecular forces between methane molecules are weak.
D Triton has a low atmospheric pressure.

C

 

[hassam]

can a ester react with carboxlic acid

no

40 Fats and grease that build up on pans used in cooking are esters. Pans which are dirty from fats
or grease may be cleaned by heating them with a reagent that will react with the ester group.
What may be used to clean such pans by this reaction?
1 vinegar - aqueous ethanoic acid, CH3CO2H
2 alcohol - ethanol, C2H5OH
3 baking powder - sodium hydrogencarbonate, NaHCO3
look at this its correct answer is 1(D) it means C.ACID reacts with ester

yea they hydrolyse it

 

[xHazeMx]

The standard enthalpy changes of formation of carbon dioxide and water are
−394 kJ mol-1 and −286 kJ mol-1 respectively.
If the standard enthalpy change of combustion of propyn, C3H4, is −1938 kJ mol-1,
what is its standard enthalpy change of formation?
A +184 kJ mol-1 C +284 kJ mol-1
B −184 kJ mol-1 D −284 kJ mol-1

A right?

 

[hassam]

 

[Zishi]

C

 

[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

 

[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..
thanks a lott

 

[xHazeMx]

A ?

 

[xHazeMx]

C

why 1 is wrong ??? :%)

 

[abdullah181994]

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

 

[hassam]

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

 

[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

no its C