It is important to balance the chemical ...

CBSE Class 10 Science 2021 Term 1 Solved Paper

Question : 10 of 60

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It is important to balance the chemical equations to satisfy the law of conservation of mass. Which of the following statements of the law is incorrect?

The total mass of the elements present, in the reactants is equal to the total mass of the elements presents in the products.
The number of atoms of each element remains the same, before amd after a chemical reaction.
The chemical composition of the reactants is the same before and after the reaction.
Mass can neither be created nor can it be destroyed in a chemical reaction.

Solution:

The 'Law of Conservation of Mass' states that:

1. Mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations.

2. The total mass of the elements present in reactants in a chemical reaction is equal to the total mass of the elements present in product.

3. The number of atoms of each element remains the same, before and after a chemical reaction.

Thus, the statement which is incorrect is given in option (c), "the chemical composition of the reactants is the same before and after the reaction."

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