‘amu’ has been replaced by ‘u’ which is known as …A… Here, A refers to — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question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: Unit of Atomic Mass **Step 1: Identify what 'amu' stands for** The term 'amu' = atomic mass unit, the older notation for expressing atomic/molecular masses. **Step 2: Understand the modern replacement** The International Union of Pure and Applied Chemistry (IUPAC) replaced 'amu' with the symbol **'u'** to standardize atomic mass measurements. **Step 3: Define what 'u' represents** The unit 'u' is called the **unified atomic mass unit** (or simply **atomic mass unit**). **Step 4: Key definition** One unified atomic mass unit (1 u) is defined as exactly $\frac{1}{12}$ of the mass of a carbon-12 atom: $$1 \text{ u} = \frac{1}{12} \text{ of }^{12}\text{C atom mass}$$ **Step 5: Verify the answer** Since the question asks what 'A' refers to when 'amu' is replaced by 'u': $$\boxed{\text{A} = \text{Unified Atomic Mass Unit (or Atomic Mass Unit)}}$$ **Note:** Both 'amu' and 'u' represent the same unit; 'u' is simply the modern IUPAC-approved notation.