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The set representing the correct order of ionic radius is

  • Option 1)

    Li^{+}> Be^{2+}> Na^{+}> Mg^{2+}

  • Option 2)

    Na^{+}>Li^{+}> Mg^{2+}> Be^{2+}

  • Option 3)

    Li^{+}> Na^{+}>Mg^{2+}> Be^{2+}

  • Option 4)

    Mg^{2+}>Be^{2+}>Li^{+}>Na^{+}>

 

Answers (2)

As we learnt in

Ionic radii of alkaline earth metals -

Elements are large but smaller than corresponding elements of group 1.

Increases down the group

- wherein

Because removal of 2 electrons increases the effective nuclear charge which pulls the electron inwards

 

and 

 

Diagonal similarity of atomic and ionic radii of lithium and magnesium -

Atomic radius of lithium is 152 pm while of magnesium is 160 pm. Ionic radius of Li^{^{+}} is 76 pm, very close to Mg^{^{2+}}which is 72 pm

-

 

Order of ionic radius

 \Rightarrow Na^{+}> Li^{+}> Mg^{2+}> Be^{2+}

 

 


Option 1)

Li^{+}> Be^{2+}> Na^{+}> Mg^{2+}

This option is incorrect.

Option 2)

Na^{+}>Li^{+}> Mg^{2+}> Be^{2+}

This option is correct.

Option 3)

Li^{+}> Na^{+}>Mg^{2+}> Be^{2+}

This option is incorrect.

Option 4)

Mg^{2+}>Be^{2+}>Li^{+}>Na^{+}>

This option is incorrect.

Posted by

Vakul

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option 2

Posted by

Piyush

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