(a)  (i)  What is meant by hardness of water?
      (ii) Describe briefly how you would determine what proportion of hardness in a given sample of water is due to permanent hardness.
     (iii) Give two reasons why hardness of water is an undesirable property.

(b)   State the:
(i)    reagents;
(ii)   conditions for the laboratory preparation of trioxonitrate (V) acid.
(iii)  How does concentrated trioxonitrate (V) acid reacts with:
(I)   sulphur;
(II)  aluminium.  

(c)   Name one amphoteric oxide.