Magnesium oxide is used for the lining in steel making furnace because

Explanation

(a). `MgO` is used for the lining of steel making furnance because it is stable at very high temperatures and it forms slag with impurities. In this manner, it helps in removing the impurities. (b). `BeCl_(2)impliesH=(1)/(2)(V+M)=(1)/(2)(2+2)=2=sp`
Where `V` is the number of valence electrons and `M` is the number of monovalent atoms attached to the central atom.
Therefore, `BeCl_(2)` is `sp` hybridised and has linear shape.

`SnCl_(2)impliesH=(1)/(2)(V+M)=(1)/(2)(4+2)=3=sp^(2)` or hybridisaton =number of bond pairs+number of lone pairs
`=2+1=3=sp^(2)`
Therefore,`SnCl_(2)` is `sp^(2)` hybridised, has planar geometry and the ions are `V-`shaped or angular in shape.