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Which of the following molecules having geometry same as H2O. 1) SO2 2)NH3 3)CO2...

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lak-86 | Student, Undergraduate | Salutatorian

Posted July 31, 2013 at 7:02 AM via web

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Which of the following molecules having geometry same as H2O.

1) SO2

2)NH3

3)CO2

4)BeCl2

5)BaO

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llltkl | College Teacher | Valedictorian

Posted July 31, 2013 at 9:12 AM (Answer #2)

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The molecular structures can be obtained in the light of VSEPR theory.

The number of electron pairs around the central atom in H2O is:

(6 (oxygen's own)+1*2(one each from each hydrogen))/2=4  --- (i)

Less pi-pairs (if any)   =0 --- (ii)

-----------------------------------------------------------------

No. of structurally active electron pairs = 4  --- (iii)

Hybridization = sp^3  ---- (iv)

Geometry = tetrahedral, out of the four points, two are lone pairs, hence type is AB2E2 ---- (v)

Molecular geometry, V-shaped or bent.

On similar treatment, the corresponding steps for SO2 are:

 (6+4)/2=5 --- (i) 

           -  2 --- (ii)

-----------------------------------------------

            3 --- (iii)

sp^2 --- (iv)

AB2E --- (v)

Final geometry of SO2 is bent, or V-shaped.

For NH3, the steps are:

(5+3)/2=4 --- (i) 

          -  0 --- (ii)

-----------------------------------------------------

            4 --- (iii)

sp^3 --- (iv)

AB3E --- (v)

Final geometry of NH3 is pyramidal.

For CO2, the parameters are:

(4+2*2)/2=4 --- (i) 

          -  2 --- (ii)

--------------------------------------------------------

            2 --- (iii)

sp --- (iv)

AB2 --- (v)

Final geometry of CO2 is linear.

For BeCl2, the parameters are:

(2+2*1)/2=2 --- (i) 

          -  0 --- (ii)

--------------------------------------------------------

            2 --- (iii)

sp --- (iv)

AB2 --- (v)

The molecular structure of BeCl2 is linear.

BaO has only one bond in the molecule. So it must be linear in geometry.

Therefore, structurally H2O is similar to SO2, though its state of hybridization is similar to NH3.
Hence correct answer is option 1).

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