The mass of one mole of a substance in grams is called its …A… Here, A refers to — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question

💡 Solution & Explanation

# Solution **The mass of one mole of a substance in grams is called its Molar Mass (or Molecular Weight).** ## Step-by-step reasoning: 1. **Definition of mole:** One mole is defined as $6.022 \times 10^{23}$ particles (Avogadro's number) of a substance. 2. **Molar mass concept:** Molar mass is the mass in grams of exactly one mole of any substance. 3. **Mathematical relationship:** $$\text{Molar Mass} = \frac{\text{Mass (in grams)}}{\text{Number of moles}}$$ 4. **Units:** Molar mass is expressed in $\text{g/mol}$ or $\text{g mol}^{-1}$. 5. **Example:** For $H_2O$: - Molar mass = (2 × 1) + 16 = 18 g/mol - This means 1 mole of water weighs 18 grams 6. **Why B is correct:** The blank A refers to **"Molar Mass"** (or equivalent terms like "Molecular Weight," "Gram Atomic/Molecular Mass"), which is the standard chemistry term for the mass of one mole of a substance expressed in grams.