Which of the following gases would have the highest average molecular speed at 25°c? a. o2b. n2c. ch4d. sf6e. co2

Answer is: c) CH₄.
Average speed is inversely proportional to the molar mass, ligher molecules travel faster. Calculate molar mass of all molecules:
a) M(O₂) = 2·16 = 32g/mol.
b) M(N₂) = 2·14 = 28 g/mol.
c) M(CH₄) = 12 + 4·1 = 16 g/mol.
d) M(SF₆) = 32 + 6·19 = 146g/mol.
e) M(CO₂) = 12 + 2·16 = 44g/mol.