Question 28 of 36intermediate🔧 ApplyMCQ1 mark

Which one of the following will have the largest number of atoms?

Exercise: EXERCISES | Q: 1.28 | (Page 27)
For More Understanding

Explanation

Option C is correct because the number of atoms in a given mass of a substance is inversely proportional to its molar mass. Since the mass is the same (1 g) for all options, the substance with the smallest molar mass will contain the largest number of atoms. Among the given options, Lithium (Li) has the smallest molar mass.

Solution Steps

  1. Step 1: The number of atoms is calculated using the formula: Number of atoms = Given MassMolar Mass×NA\frac{\text{Given Mass}}{\text{Molar Mass}} \times N_A

  2. Step 2: Since the given mass is 1 g for all options and NAN_A (Avogadro constant) is constant, the number of atoms depends entirely on the molar mass. The smaller the molar mass, the larger the number of atoms.

  3. Step 3: The molar masses are approximately: Au = 197 g/mol, Na = 23 g/mol, Li = 7 g/mol, and Cl2Cl_2 = 71 g/mol.

  4. Step 4: Since Lithium (Li) has the lowest molar mass (7 g/mol), 1 g of Li will contain the maximum number of moles, and consequently, the largest number of atoms.

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