Atoms and Molecules

This original revision companion supports the official NCERT book; it does not replace it.

Focus

Use symbols, formulae, valencies, and the mole idea with correct units and ratios.

Common mistake

Do not change a chemical formula to balance an equation.

10-minute routine

1. Read the matching section in the official NCERT book ↗.
2. Write three key ideas without looking.
3. Take the Class 9 practice quiz ↗.
4. Check your score in My Practice ↗.

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