Assertion : Solution of Na2CrO4 in water is coloured.Reason : Oxi

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 Multiple Choice QuestionsMultiple Choice Questions

131.

Which of the following reaction involves oxidation and reduction ?

  • NaBr + HCl  NaCl + HBr

  • HBr + AgNO3  AgBr + HNO3

  • H2 + Br2  2HBr

  • Na2O + H2SO4  Na2SO4 + H2O


132.

What is the oxidation number of chlorine in ClO3- ?

  • + 5

  • + 3

  • + 4

  • + 2


133.

How many electrons are involved in oxidation of KMnO4 in basic medium ?

  • 1

  • 2

  • 5

  • 3


134.

Assertion : Ozone is a powerful oxidising agent in comparison to O2.

Reason : Ozone is diamagnetic but O2 is paramagnetic.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


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135.

The ratio of Fe2O3 and Al, in thermite is :

  • 1 : 3

  • 1 : 2

  • 3 : 1

  • none of these


136.

Which of the following reaction is a redox reaction ?

  • P2O5 + 2H2 H4P2O7

  • 2AgNO3 + BaCl2  2AgCl + Ba(NO3)2

  • BaCl2 + H2SO4  BaSO4 + 2HCl

  • Cu + 2AgNO3  Cu(NO3)2 + 2Ag


137.

What is 'A' in the following reaction ?

2Fe3+(aq) + Sn2+(aq)  2Fe2+(aq) + A

  • Sn3+(aq)

  • Sn4+(aq)

  • Sn2+(aq)

  • Sn


138.

Oxidation state of Fe in Fe3O4 is :

  • 3/2

  • 5/4

  • 4/5

  • 8/3


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139.

Assertion : Solution of Na2CrO4 in water is coloured.

Reason : Oxidation state of Cr in Na2CrO4 is +6.

  • If both assertion and reason are true and the reason is the correct explanation of the assertion.

  • If both assertion and reason are true and the reason is not the correct explanation of the assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


B.

If both assertion and reason are true and the reason is not the correct explanation of the assertion.

Na2CrO4 solution in water is yellow in colour, when acidified changes to orange colour (due to the formation of Cr2O72- ions).

Na2CrO4 + H2SO4 → Na2Cr2O7 + Na2SO4 + H2O

Oxidation state : Na2CrO4

Let oxidation state of Cr be x.

⇒ 2(+1) + + 4(-2) = 0 ⇒ x = +6.


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140.

Assertion : PbI4 is a stable compound.

Reason : Iodide stabilizes higher oxidation state.

  • If both assertion and reason are true and the reason is the correct explanation of the assertion

  • If both assertion and reason are true and the reason is not the correct explanation of the assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


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