Why the mole concept decides your whole chemistry grade If there's one topic that quietly controls more of your marks than any other, it's this one. Almost every numerical question you'll face from Class 9 all the way to A Level — percentage composition, empirical formulas, gas volumes, titrations, even electrochemistry later on — is really just the mole concept wearing a different costume. So if you've ever felt like "I understand chemistry, but I keep losing marks in the calculations," this is almost always where the gap is. Let's fix that properly, from the ground up. What a mole actually is (without the textbook fog) A mole is just a counting unit — like a "dozen," except instead of 12, it counts 6.022 × 10²³ particles. That number is called Avogadro's number . Why such a strange number? Because atoms are unimaginably small and light. If you tried to count atoms one by one, or weigh out "one atom" of carbon, you'd...
Free FBISE Board Chemistry notes, MCQs, past papers and interactive tools for Class 9-12, plus IGCSE, O Level, AS & A Level students.