Answer:
The ping pong ball, the light molecules have greater speed
Step-by-step explanation:
The kinetic energy of an object is defined as

where
m is the mass of the object
v is its speed
It follows that the speed can be written as

In this problem, both the golf ball and the ping pong ball have kinetic energy K. However, the mass of a gold ball is larger (approx. 45 g) than that of a ping pong ball (approx. 4 g): therefore, since v is inversely proportional to the square root of the mass, it follows that the ping pong ball must have a greater speed in order to achieve the same kinetic energy of the golf ball.
The same argument can be applied to the gaseous mixture: if there are more massive molecules and light molecules, and if they all have the same kinetic energy, then this means that the light molecules must have a greater speed, as a result again of the equation
