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🧪 Chemistry  ·  Some Basic Concepts of Chemistry  ·  NEET & JEE

If 0.25 mol of an element weighs 16 g, its atomic mass is:

Answer: 64.

  • A 32
  • B 4
  • C 64
  • D 8

Correct answer: C. 64

Explanation: Atomic mass = mass / moles = 16 / 0.25 = 64 u.

Mass (g)given substanceMoles (n)amount of substanceParticlesatoms / moleculesGas Volumeat STP (litres)divide byMolar Massmultiply by6.022 x 10^23multiply by22.4 L/mol

Mass connects to moles via molar mass, and moles connect to particle count via Avogadro's number or to gas volume via the 22.4 L/mol rule at STP.

Concept context

The mole is chemistry's counting unit. Learn to relate mass, volume, and number of particles using Avogadro's number and molar mass, the foundation of all stoichiometry and reaction calculations.

Read the full Some Basic Concepts of Chemistry notes →