‘amu’ has been replaced by ‘u’ which is known as …A… Here, A refers to — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question

💡 Solution & Explanation

# Solution: Understanding the Unit Change from 'amu' to 'u' **Step 1: Identify what 'amu' stands for** - 'amu' = atomic mass unit (the old notation) **Step 2: Understand the replacement** - Modern IUPAC standards have replaced 'amu' with the simpler notation 'u' - Both represent the same physical quantity: $\frac{1}{12}$ of the mass of a carbon-12 atom **Step 3: Determine what 'u' is called** - The term 'u' is known as the **unified atomic mass unit** (or simply **unified mass unit**) - It's a unified standard because it's used universally for both atomic and molecular masses **Step 4: Why this name?** - "Unified" emphasizes that this single unit applies consistently across all atomic and molecular mass measurements - It replaced older, inconsistent systems that used different standards --- **Answer: A = "unified atomic mass unit" (or "unified mass unit")** The change from 'amu' to 'u' modernizes notation while maintaining the same fundamental definition based on $^{12}C$ as the reference standard.