Which of following has the maximum number of atoms?A 20 gm of H2O B 20 gm of CH4 C 20 gm of O2 D 20 gm of CO2

To answer this question, we need to calculate the number of moles in each substance, because 1 mole of any substance contains the same number of entities (atoms, molecules, etc.), which is Avogadro's number (6.022 x 10^23).

The number of moles is calculated by dividing the mass of the substance by its molar mass.

1. For H2O: The molar mass of H2O is 18 g/mole (16 for Oxygen and 1 for each Hydrogen). So, the number of moles in 20 g of H2O is 20/18 = 1.11 moles. Since each molecule of H2O contains 3 atoms (2 Hydrogen and 1 Oxygen), the total number of atoms is 1.11 * 3 = 3.33 moles of atoms.

2. For CH4: The molar mass of CH4 is 16 g/mole (12 for Carbon and 1 for each Hydrogen). So, the number of moles in 20 g of CH4 is 20/16 = 1.25 moles. Since each molecule of CH4 contains 5 atoms (1 Carbon and 4 Hydrogen), the total number of atoms is 1.25 * 5 = 6.25 moles of atoms.

3. For O2: The molar mass of O2 is 32 g/mole (16 for each Oxygen). So, the number of moles in 20 g of O2 is 20/32 = 0.625 moles. Since each molecule of O2 contains 2 atoms (both Oxygen), the total number of atoms is 0.625 * 2 = 1.25 moles of atoms.

4. For CO2: The molar mass of CO2 is 44 g/mole (12 for Carbon and 16 for each Oxygen). So, the number of moles in 20 g of CO2 is 20/44 = 0.45 moles. Since each molecule of CO2 contains 3 atoms (1 Carbon and 2 Oxygen), the total number of atoms is 0.45 * 3 = 1.36 moles of atoms.

So, 20 g of CH4 has the maximum number of atoms.