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Which of the statements is not true?

  • Option 1)

    On passing H_{2}S through acidified K_{2}Cr_{2}O_{7} solution, a milky colour is observed.

  • Option 2)

    Na_{2}Cr_{2}O_{7} is preferred overK_{2}Cr_{2}O_{7} in volumetric analysis.

  • Option 3)

    K_{2}Cr_{2}O_{7} solution in acidic medium is orange.

  • Option 4)

    K_{2}Cr_{2}O_{7} solution becomes yellow on increasing pH beyond 7.

 

Answers (1)

best_answer

As we learned in concept

Oxidation states -

Transition elements have a variety of oxidation states but the common oxidation state is +2 for 3d metals.

 

-

 

 Number of oxidation states displayed by d block elements = no. of electrons in d orbitals (unpaired) + no. of electrons in s orbitals

Oxidation states in 3d^{5}4s^{2}=5+2=7

Oxidation states in 3d^{5}4s^{1}=5+1=6

Oxidation states in 3d^{2}4s^{2}=2+2=4

Oxidation states in 3d^{3}4s^{2}=3+2=5

 


Option 1)

On passing H_{2}S through acidified K_{2}Cr_{2}O_{7} solution, a milky colour is observed.

This option is incorrect.

Option 2)

Na_{2}Cr_{2}O_{7} is preferred overK_{2}Cr_{2}O_{7} in volumetric analysis.

This option is correct.

Option 3)

K_{2}Cr_{2}O_{7} solution in acidic medium is orange.

This option is incorrect.

Option 4)

K_{2}Cr_{2}O_{7} solution becomes yellow on increasing pH beyond 7.

This option is incorrect.

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Aadil

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