Give reasons for the following:

1.	Give reasons for the following:
Answer» `BeO` is used as a refractory material. Beryllium halides are polymeric. `Be(OH)_(2)` dissolves in `NaOH`, but `CA(OH)_(2)` does not On hydrolysis at ROOM temperature, `Mg_(3)N_(2)` gives AMMONIA, whereas `MgCl_(2)` gives `HCl`. Solution :`BeO` has high lattice enthalpy due to smaller ionic size and greater charge on `Be^(2+)` and `O^(2-)` ions. Hence, `beO` has high melting point and is used as a refractory material. (b).Beryllium halides are electron-deficient compounds since they only four electrons in the valence shell. to complete their octet, they undergo polymerisation. (C ). `Be(OH)_(2)` being amphoteric dissolves in `NaOH` forming sodium beryllate. `Be(OH)_(2)+2NaOHrarrNa_(2)BeO_(2)+2H_(2)O` Whereas `Ca(OH)_(2)` being basic, does not dissolve in `NaOH`. (d). `Mg_(3)N_(2)` is a salt of strong base `[Mg(OH)_(2)]` and a weak acid `(NH_(3))` and hence on hydrolysis gives `NH_(3)`. `Mg_(3)N_(2)+6H_(2)Orarr3Mg(OH)_(2)+2NH_(3)` `MgCl_(2)` is a salt of strong base, `Mg(OH)_(2)`, and strong acid, `HCl`, and hence does not hydrolyse.

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