Question

becl2 is a linear molecule while h2o is an angular molecule give reason​

Answer 1

Using the concept of hybridization it can be explained.

Shortcut formula to find hybridization(let X) is-

   X=SA +1/2 * (G-V+/- a)

here, SA=surrounding atoms

G=ground state valency of central atom

V=valency of central atom in given species

+/-a=charge on given species

If X=2 --> sp hybridised

   X=3 --> sp² hybridised

   X=4 --> sp³ hybridised

   X=5 --> sp³d hybridised 

and so on....

So,

Using this formula,

BeCl2 is sp hybridised, so it has linear geometry

and SCl2 is sp³ hybridised, so it has tetrahedron geometry, having angle 109.5°!

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Hope this is helpful to you