Which one of the following gases would have the highest average molecular speed at 25 °C?

Answer 1

The gas with the highest average molecular speed at 25 °C would be hydrogen (H2), as it has the lowest molar mass of all the options listed. According to the equation for average molecular speed, average molecular speed is inversely proportional to the square root of the molar mass of the gas. So, gases with lower molar masses will have higher average molecular speeds at the same temperature.