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Class X CBSE Science important topics

 Chemical Reaction and Equations


Q1. What is the meaning of chemical reaction?

Ans: It is a process which transforms one or more substances into new substances with new properties.

Q2. What is chemical equations?

Ans: A chemical equation is a statement used in chemistry to represent a chemical reaction.

Q3. What are reactants?

Ans: The substances which take part in a chemical reaction are called reactants.

Q4. What are products?

Ans: The substance which are formed as a result of chemical reactions are called products.

Q5. What is the meaning of balanced chemical equation?

Ans: The chemical equation in which total number of atoms of reactants is equal to the total number of atoms of products is known as 'Balanced Chemical Equation'.

Q6. What is skeletal equation?

Ans: A chemical equation in which the number of atoms of each kind are not equal in the reactants and products is called unbalanced chemical equation or skeletal equation.

Q7. What method we can use to balanced chemical equation?

Ans: Hit and trial method

Q8. What are the common representations in chemical equation?

Ans: Common representations are:

⚫Solid : (s)

⚫Liquid : (l)

⚫gas : (g)

⚫solution in water : (aq)

⚫Evolution of gas : (↑)

⚫Formation of precipitate : (↓)

Q9. What is chemical formula?

Ans: A brief representation of a substance in terms of symbols of various elements present in it called chemical formula.

Q10. What are exothermic reactions?

Ans: The chemical reactions which proceed with the evolution of heat are called exothermic reactions.

     Reactant  + Product --->Heat  (Exothermic Reaction)



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