International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

What is Avogadro's number?

1. 3.01 x 10²³

2. 6 x 10²²

3. 6 x 10²³

4. 1.20 x 10²⁴

The correct answer is: 6 x 10²³

Avogadro's number is a fundamental constant in chemistry, representing the number of particles, typically atoms or molecules, in one mole of a substance. This number is approximately 6.022 x 10²³. It is essential for converting between the macroscopic scale of substances (grams, liters) and the microscopic scale (particles, molecules) during calculations in stoichiometry. The correct response accurately reflects this constant, aligning closely with its widely accepted value, which is crucial for any calculations involving moles in chemical reactions. Understanding Avogadro's number allows chemists to quantify relationships in chemical equations and determine the amounts of reactants and products in a reaction. It highlights the relationship between the atomic scale and the macroscopic scale that we observe in laboratory settings.