The heat of combustion of carbon to CO2 is -393.5 kJ/ mol. The he

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 Multiple Choice QuestionsMultiple Choice Questions

241.

For the decomposition of a compound AB at 600 K, the following data were obtained
[AB] mol dm-3 Rate of decomposition of AB in mol dm-3
0.20 2.75 × 10-8
0.40 11.0 × 10-8
0.60 24.75 × 10-8

The order for the decomposition of AB is

  • 1.5

  • 0

  • 1

  • 2


242.

The oxidation state of fe in the brown ring complex : [Fe(H2O)5NO]SO4 is

  • +3

  • 0

  • +2

  • +1


243.

A miscible mixture of C6H6 + CHCl3 can be separated by

  • sublimation

  • distillation

  • filtration

  • crystallisation


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244.

The heat of combustion of carbon to CO2 is -393.5 kJ/ mol. The heat released upon formation of 35.2 gm of CO2 from carbon and oxygen gas is:

  • +315 kJ

  • -31.5 kJ

  • -315 kJ

  • +31.5 kJ


C.

-315 kJ

Given, 

Heat of combustion of C to CO2 = -393.5 kJ/ mol

Molecular mass of CO2 = 12 + 16 × 2 = 44 gm

C (s) + O2 (g) → CO2 (g); H = -393.5 kJ

 Heat of formation of (1 mole) 44 gm

CO2 = -393.5 kJ

 Heat of formation of (1 mole) 1g

CO2-393.544 kJ

 Heat of formation of (1 mole)

35.2 g CO2-393.5 × 35.244

                = -314.8 kJ

                = -315 kJ


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245.

Which of the following substances acts as an oxidising as well as a reducing agent ?

  • Na2O

  • SnCl2

  • Na2O2

  • NaNO2


246.

The compound having the lowest oxidation state of iron is :

  • K4Fe(CN)6

  • K2FeO4

  • Fe2O3

  • Fe(CO)5


247.

3ClO-(aq) → ClO- + 2Cl is an example of

  • Oxidation reaction

  • reduction reaction

  • disproportionation reaction

  • decomposition reaction


248.

When K2Cr2O7 is converted into K2CrO4, the change in oxidation number of chromium is :

  • 0

  • 5

  • 7

  • 9


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249.

In the equation

CrO42- + SO32-  Cr(OH)4- + SO42-

the oxidation number of Cr changes from

  • +6 to +4

  • +6 to +3

  • +8 to +4

  • +4 to +3


250.

Which quantities are conserved in all oxidation- reduction reactions?

  • Charge only

  • Mass only

  • Both charge and mass

  • Neither charge nor mass


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