L. 2.0 g of a metal burnt in oxygen gave 3.2 g of its oxide. 1.42 g of the same metal heated in steam

In first  reaction :

3.2 g of metal oxide contains 2g metal 

\(\therefore\) % of metal in metal oxide is  \({2\over 3.2}\times 100=62.5 \%\)

and % of oxygen in metal oxide is  \({1.2\over 3.2}\times 100 =37.5\%\) 

In second reaction :

2.27 g of metal oxide contains 1.42 g of metal 

\(\therefore\) % of metal in metal oxide is \({1.42\over 2.27}\times 100=62.5 \%\) 

and % of oxygen in metal oxide is \({0.85\over 2.27}\times 100=37.5\%\)  

the percentage of metal and oxygen in both reaction is nearly same , 

according to law of definite proportion  "a given compund always conatins exactly the same proportion of elements by  weight" 

, hence  The law of definite proportion is verified by the given data