The average speed of gas molecules in cylinders a, b, c, and d are 0.001 m/s, 0.05 m/s, 0.1 m/s, and 0.0005 m/s, respectively. which cylinder contains gas that is closest to absolute zero

In order to know this you need to have in mind the following: Normaly, speed of gas molecules depends on temperature. That means that the lower the temperature, the slower the molecules. For this case, the slowest is the closest to absolute zero. So your answer is 0.0005 m/s