EXERCISE - I Question 1. (a) Define a chemical reaction. Answer: Any chemical change in matter which involves transformation into one or more substances with entirely different properties is called a chemical reaction. (b) What happens during a chemical reaction ? Answer: A chemical reaction involves breaking of chemical bonds between the atoms or groups of atoms of reacting substances and rearrangement of atoms making new bonds to form new substances. (c) What do you understand by a chemical bond ? Answer: (b) A chemical reaction involves breaking of chemical bonds between the atoms or groups of atoms of reacting substances and rearrangement of atoms making new bonds to form new substances. (c) A chemical bond is the attractive force that holds the atoms of a molecule together, in a compound. Question 2. Give one example each of which illustrates the following characteristics of a chemical reaction: (a) evolution of a gas (b) change of colour (...
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