Problem $\backslash$#$1$

An ideal gas, at $\backslash (20^\{\backslash$circ$\}\backslash$mathrm$\{$C$\}\backslash )$ and $1$ atm $,$ flows at $\backslash (12\backslash$mathrm$\{$~m$\}/\backslash$mathrm$\{$s$\}\backslash )$ past a thin flat plate. At a position $0\mathrm{.}60$ m downstream from the leading edge, the boundary layer thickness is $5$ mm $.$ Which of the $12$ gases in the table below is this likely to be$?$ The table gives properties of gases at $1$ atm and $\backslash (20^\{\backslash$circ$\}\backslash$mathrm$\{$C$\}\backslash ).($Hint: assume the flow is laminar.$)$