Mass is not conserved in chemical reactions. Mass is therefore never conserved because a little of it turns into energy in every reaction
Explanation: This is a reaction of oxidation of 
in the presence of acidified 
. Acidified is a strong oxidizing agent.
To balance out the 
on the reactant side, we write 
on the product side.
Balancing out the following reaction gives us:
Answer:
0.72 g of the lower oxide gave 0.8 g of higher oxide when oxidised. ... Thus, 90g of lower oxide contains as much metal as 100g of higher oxide, i.e., 80g (given). Hence, 80g of metal combines with 10g of oxygen in the lower oxide and 20g of oxygen in the higher oxide.
