NCERT Solutions for class 10 Science Chapter 1 - Chemical Reactions and Equations - eSaral

Chapter 1 covers five core topics: writing and balancing chemical equations, and five types of reactions — combination, decomposition, displacement, double displacement, and redox (oxidation-reduction). It also covers real-life applications like corrosion and rancidity. All NCERT in-text and exercise questions on these topics are solved in the eSaral PDF.

Start by writing the unbalanced equation with correct formulas. Count atoms of each element on both sides. Adjust coefficients (not subscripts) to make atom counts equal on both sides. Begin with the most complex molecule and balance hydrogen and oxygen last. Always verify by recounting atoms after balancing. The law of conservation of mass must hold for every balanced equation.

The five types are: (1) Combination — two substances form one product; (2) Decomposition — one substance splits into two or more; (3) Displacement — a reactive metal replaces a less reactive metal from its salt; (4) Double Displacement — ions of two compounds swap to form new compounds; (5) Redox — simultaneous oxidation and reduction occur. Each type has a distinct pattern students can use to identify reactions quickly.

Corrosion affects metals — it is the gradual degradation of metals like iron (rusting) due to reaction with oxygen and moisture. Rancidity affects food — it occurs when fats and oils are oxidised, causing unpleasant smell and taste. Both are harmful oxidation reactions. Corrosion is prevented by painting or galvanising; rancidity is prevented by antioxidants, airtight storage, or nitrogen-flushed packaging.

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