Out of chlorine, ethylene ,helium ,hydrogen and nitrogen which one of those gases would flow more readily along the ground if accidentally released

Out of the given options, helium would flow more readily along the ground if accidentally released. Helium is the lightest gas and thus has lower density compared to other gases. As a result, it has a higher tendency to disperse quickly and rise upwards, making it less likely to stay close to the ground for an extended period.