Question

aluminium carbide contains 75% of Al,aluminium oxide contains 52.9% of Al & carbon dioxide contains 27.27% of C.show that these figures illustrate the law of reciprocal proportion

Answer 1

Aluminum carbide contains 75% of Al and  25% of C.
     So  3 grams of Al  combines with 1 gram of C. 
     Or,  ratio  Al : C  = 3 : 1

Aluminum oxide contains  52.9% of Al and  47.1% of Oxygen.
   So  ratio  Al : O  = 52.9 :  47.1  =  1.123 :  1
                             or,     3 : 2.671

Carbon dioxide contains 27.27 % of C and  72.73% of O.
   So ratio  C :  O  =  27.27 : 72.73
               or ,    1 : 2.667    or nearly  equal to  2.671  above.

So  carbon and Oxygen combine in the same ratio as they reacted with Aluminum.