Page 2 - Microsoft Word - Home assignment-P Block Elements

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Q26. [SiF 6] is known where as [SiCl 6] is not. Give two reasons.
Q27. Write reactions to justify amphoteric nature of Al?
Q28. What happens when
(i)Borax is heated strongly

(ii)Boric acid is added to water
(iii)Al is treated with NaOH

(iv)BF3 reacts with NH3
(v)ZnO is heated with CO.

(vi)SiO 2 is treated with HF.
(vii)Hydrated alumina is treated with aqueous NaOH solution.
Q29. Give reason for the following.

(i)Conc. HNO3 can be transported in aluminium containers.
(ii)A mixture of NaOH and Al pieces is used to open the drain.
(iii)Aluminium utensils should not be kept in water over night’

(iv)Aluminium alloys are used to make aircraft body.
(v)Aluminium wire is used to make transmission cables.
(vi)Diamond is covalent, yet it has high melting point.

Q30. Complete the following reactions.
(i) B2H6 + H2O →
(ii)B2H6 + NaH →
(iii)BF3 + LiH →

(iv) H 3BO 3 heat
(v) B2H6 + NH3 →
(vi)Na2B4O7.10H2O heat

(vii) Na2B4O7 + 7H2O →
(viii)BCl3 + LIAlH4 →