The average molecular speed in a sample of Ar gas at a certain temperature is 391 m/s. The average molecular speed in a sample of Ne gas is m/s at the same temperature.

550 m/s

Explanation:

The average molecular speed (v) is the speed associated with a group of molecules on average. We can calculate it using the following expression.

where,

We can use the info of argon to calculate the temperature for both samples.

Now, we can use the same expression to find the average molecular speed in a sample of Ne gas.

i think   the answer is c hope i'm right