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### Question Asked by a Student from EXXAMM.com Team

** Q 1115601569. ** At `400 K,` the root mean square (rms) speed of a gas `X` (molecular weight = `40`) is equal to the most probable speed (mp) of gas `Y` at `60` K. The molecular weight of the gas `Y` is

**JEE 2009 **

#### HINT

Use formula: `U_(rms) = sqrt ((3RT)/M)`
`U_(mp) = sqrt ((2RT)/(M))`