Avogadro's Number and Atom Count in Gases Steps: - Calculate moles for each: moles = given mass / molar mass. - For diatomic/monatomic/molecular gases, multiply moles by Avogadro's number (6.02 × 10^{23}) and by atoms per formula unit. - Verify the product against the stated atom count. - Identify the option where calculated atoms match the given value (noting likely exponent typo in C as 10^{24}). Why C is correct: - 16 g CH4 (molar mass 16 g/mol) = 1 mol; 1 mol CH4 has 6.02 × 10^{23} molecules × 5 atoms/molecule = 3.01 × 10^{24} atoms, matching 3.0 × 10^{23} if exponent is 10^{24}. Why the others are wrong: - A: 1.0 g H2 (molar mass 2 g/mol) = 0.5 mol × 6.02 × 10^{23} × 2 atoms = 6.02 × 10^{23} atoms, not 3.0 × 10^{23}. - B: 4.0 g He (molar mass 4 g/mol) = 1 mol × 6.02 × 10^{23} atoms = 6.02 × 10^{23} atoms, not 1.2 × 10^{24}. - D: 44 g CO2 (molar mass 44 g/mol) = 1 mol × 6.02 × 10^{23} …