It takes 192 sec for an unknown gas to diffuse through a porous wall and 84 sec for `N_(2)` gas to efffuse at the same temperature and pressure. What is the molar mass of the unknown gas?

Explanation

`gamma_("unknown")/(gammaN_(2))=(t_(N_(2)))/(t_("unknown"))=sqrt((m_(N_(2)))/(m_("unknown")))`
`(84sec)/(192sec)=sqrt((28gmol^(-1))/(m_("unknown")))=(28gmol^(-1))/(m_("unknown"))`
`m_("unknown")=28mol^(-1)xx((192sec)/(84sec))^(2)`
`m_("unknown")=146.28gmol^(-1)`.