Answer:
The correct option is methane :.
Explanation:
Average speed of the gas molecules id given by expression:
k = Boltzmann cosnatnt
T = Temperature of the gas molecules = 355 K
m = molecular mass of the molecule
Molar mass of methane = 18 g/mol
Molar mass of neon = 20.18 g/mol
Molar mass of ethene = 28 g/mol
Molar mass of chlorine gas = 70 g/mol
Lower the value of molar mass of gas molecule higher will be the average speed.So, from the given options methane gas greatest average seed because it has lowest molecular mass