Ncert Exercises & Solutions

Which of the following statements about the reaction given below is correct?

$4 Fe (s) + 3 O_{2} (g) \to 2 {Fe}_{2} O_{3} (g)$

1.	Total mass of iron and oxygen in reactants = total mass of iron and oxygen in product therefore it follows the law of conservation of mass
2.	Total mass of reactants = total mass of product, therefore, the law of multiple proportions is followed
3.	The amount of Fe₂O₃ can be increased by taking any one of the reactants (iron or oxygen) in excess.
4.	The amount of Fe₂O₃ produced will decrease if the amount of any one of the reactants (iron or oxygen) is taken in excess.

1. HINT: Limiting reagent concept

According to the law of conservation of mass,

Total mass of reactants = Total mass of products

Amount of Fe₂O₃ is decided by limiting reagent.