Which among the following has the highest mass?

To determine the highest mass, we calculate the mass for each option. 1) 12 x 10^24 atoms of H2 is approximately 20 moles (since 12 x 10^24 / 6.022 x 10^23 ≈ 20). As H2 has a molar mass of 2 g/mol [c1], the mass is ~40 g. 2) 20 g of S is given directly. 3) 2 gram-equivalents of Na2CO3: The molar mass of Na2CO3 is 106 g/mol [t4]. Since the n-factor for Na2CO3 is 2, the equivalent weight is 53 g. Thus, 2 equivalents equal 106 g. 4) 4 mol of CO2: The molar mass of CO2 is 44 g/mol [t4]. Therefore, 4 moles weigh 4 x 44 = 176 g. Comparing 40 g, 20 g, 106 g, and 176 g, the 4 moles of CO2 have the highest mass [t1][t6].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.2.4 Homologous Series > p. 66
2. [2] https://www.khanacademy.org/science/hs-chemistry/x2613d8165d88df5e:stoichiometry-and-the-mole/x2613d8165d88df5e:moles-and-molar-mass/v/calculations-using-avogadro-s-number-part-1